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$BDI@n(B $B=$0l(B
<shui @ cs.tsukuba.ac.jp>

$B$3$N%Z!<%8$O!$ http://www.coins.tsukuba.ac.jp/~syspro/2005/No2.html
$B%7%9%F%`%W%m%0%i%`$N%[!<%`%Z!<%8!J(B2005$BG/EY!K(B
http://www.coins.tsukuba.ac.jp/~syspro/2005/
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  #include <stdio.h>
  
  main()
  {
          printf("hello world!\n");
  }
  

  $B$5$i$K>\$7$$2r@b(B

  $B?7>k@h@8$,=q$+$l$?2r@b$r;2>H$7$F$/$@$5$$!%(B
  http://www.hlla.is.tsukuba.ac.jp/~yas/classes/ipe/nitiniti2-enshu-1996/1996-11-18/kanji-code.html

  C$B8@8l$K$*$1$kJ8;z$HJ8;zNs(B

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  char c;
  c = 'A';        /* (1) */
  c = 0x41;       /* (2) */
  

  $BJ8;z$O?tCM$G$"$k$?$a!$1i;;$dHf3S$NBP>]$K$J$k!%(B $B2<$N%W%m%0%i%`$G$O!$(Bchar $B7?$NJQ?t(B c $B$r(B ++ $B$G%$%s%/%j%a%s%H!J(B7$B9TL\!K$7$?$j!$(B<= $B$GJ8;zDj?t$HHf3S!J(B6$B9TL\!K$7$F$$$k!%(B

       1  #include <stdio.h>
       2
       3  main()
       4  {
       5          char c = 'a';
       6          while (c <= 'z')
       7                  putchar(c++);
       8          putchar('\n');
       9  }
  

  $BJ8;zNs(B

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       1  #include <stdio.h>
       2
       3  char s[] = {'H', 'e', 'l', 'l', 'o', 0};
       4
       5  main()
       6  {
       7          int     i = 0;
       8
       9          printf("%s\n", s);
      10
      11          while (s[i]) {
      12                  printf("[%d] = %c\n", i, s[i]);
      13                  i++;
      14          }
      15  }
  

  3$B9TL\$G$O!$J8;z7?G[Ns(B s $B$K=gHV$K(B Hello $B$HF~$k$h$&$K=i4|2=$7$F$$$k!%(B 9$B9TL\$N(B printf $B$G$OJQ49J8;z$K(B %s $B$rMQ$$$F!$J8;zNs$r=PNO$7$F$$$k!%(B $B$3$l$GJ8;z7?G[Ns(B s $B$,J8;zNs$H$J$C$F$$$k$3$H$,$o$+$k!%(B 11$B!A(B14$B9TL\$G$O!$J8;z7?G[Ns(B s $B$N3FMWAG$NJ8;z$r=PNO$7$F$$$k!%(B 12$B9TL\$N(B printf $B$G$OJQ49J8;z$K(B %c $B$rMQ$$$F!$J8;z$r=PNO$7$F$$$k!%(B $B$3$l$r%3%s%Q%$%k

  % ./a.out 
  Hello
  [0] = H
  [1] = e
  [2] = l
  [3] = l
  [4] = o
  %
  

  3$B9TL\$O!$0J2<$N$h$&$K=q$$$F$bF1$8$G$"$k!%(B

       3  char s[] = "Hello";
  

  $B$7$+$7$J$,$i!$0J2<$N(B$B%W%m%0%i%`(B$B$N$h$&$K=q$/$H!$0UL#$,0[$J$C$F$/$k!%(B 3$B9TL\$G$O!$(Bchar $B%]%$%s%?7?$NJQ?t(B ps $B$KJ8;zNs$,BeF~$5$l$F=i4|2=$5$l$F$$$k!%(B $B>e5-$NJ8;z7?G[Ns(B s $B$O!$=i4|CM$H$J$kJ8;zNs$H=*C$C$F!$%W%m%0%i%`Cf$G$3$N%]%$%s%?$rB>$N>l=j$r;X$9$h$&$KJQ99$9$k$3$H$,$G$-$k!%(B $B5U$K!$J8;zNsDj?t$NFbMF$NJQ99$N7k2L$O!J8@8l;EMM>e$O!KITDj$G$"$k!%(B Linux$B$G$ODL>o%;%0%a%s%F!<%7%g%s%U%)%k%H$,H/@8$7%W%m%0%i%`$O0[>o=*N;$7$F$7$^$&$,!$$G$-$F$7$^$&(BOS$B$b$"$k!%(B

       1  #include <stdio.h>
       2
       3  char *ps = "Hello";
       4
       5  main()
       6  {
       7          int     i = 0;
       8
       9          printf("%s\n", ps);
      10
      11          while (*ps) {
      12                  printf("[%d] = %c\n", i, *ps);
      13                  i++;
      14                  ps++;
      15          }
      16  }
  

  $B>e5-%W%m%0%i%`(B14$B9TL\$G$O%]%$%s%?$r%$%s%/%j%a%s%H$9$k$3$H$K$h$j!$

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      11          while (*ps)
      12                  printf("[%d] = %c\n", i++, *ps++);
  

  $BI8=`F~=PNO(B

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  int    getchar(void);
  char * gets(char *s);
  int    scanf(const char *format, ...);
  

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  int    putchar(int c);
  int    puts(const char *s);
  int    printf(const char *format, ...);
  

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  fgets$B$KBP1~$9$kJ8;z!$9T!$=q<0IU$-$NF~=PNO$r9T$&%i%$%V%i%j4X?t$K$O0J2<$N$b$N$,$"$k!%(B

  int    fgetc(FILE *stream);
  char * fgets(char *s, int size, FILE *stream);
  int    fscanf(FILE *stream, const char *format, ...);
  int    fputc(int c, FILE *stream);
  int    fputs(const char *s, FILE *stream);
  int    fprintf(FILE *stream, const char *format, ...);
  

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  $BI8=`F~=PNO$K$O!$I8=`=PNO$G$"$k(B stdout $B$NB>$K!$I8=`%(%i!<=PNO$H8F$P$l$k$b$&0l$D=PNO$N8}$,$"$k!%(B $BI8=`%(%i!<=PNO$O(B stream $B$K(B stderr $B$H=q$/$3$H$G;XDj$G$-$k!%(B $BI8=`%(%i!<=PNO$O!$%(%i!<%a%C%;!<%8$d7Y9p$N%a%C%;!<%8$J$INc30E*$J=hM}$K4X$9$k%a%C%;!<%8$r=PNO$9$k$?$a$K;HMQ$5$l$k!%(B

  $B0J2<$O(B getchar $B$K$h$jI8=`F~NO$+$i(B1$BJ8;zFI$_9~$_!$(Bputchar $B$K$h$jI8=`=PNO$X(B1$BJ8;z=q$-=P$9%W%m%0%i%`$G$"$k!%(B

       1  #include <stdio.h>
       2
       3  main()
       4  {
       5          int     c;
       6
       7          while ((c = getchar()) != EOF)
       8                  putchar(c);
       9  }
  

  $B$3$l$r%3%s%Q%$%k

  % ./a.out 
  1234567890 
  1234567890
  abcdefg 
  abcdefg
  
  %
  

  fgetc, fputc $B$r;HMQ$9$k$H0J2<$N(B$B%W%m%0%i%`(B$B$N$h$&$K$J$k!%(B $B7k2L$O!$(Bgetchar, putchar $B$r;HMQ$7$?>l9g$H!$A4$/F1$8$K$J$k!%(B

       1  #include <stdio.h>
       2
       3  main()
       4  {
       5          int     c;
       6
       7          while ((c = fgetc(stdin)) != EOF)
       8                  fputc(c, stdout);
       9  }
  

  $B0J2<$O(B fgets $B$K$h$jI8=`F~NO$+$i(B1$B9TFI$_9~$_!$(Bputs $B$K$h$jI8=`=PNO$X(B1$B9T=q$-=P$9(B$B%W%m%0%i%`(B$B$G$"$k!%(B

       1  #include <stdio.h>
       2  
       3  #define LINE_LEN        80
       4  
       5  main()
       6  {
       7          char    line_buf[LINE_LEN];
       8  
       9          while (fgets(line_buf, LINE_LEN, stdin) != NULL)
      10                  puts(line_buf);
      11  }
  

  $B$3$l$r%3%s%Q%$%k

  % ./a.out 
  1234567890
  1234567890
  
  abcdefg
  abcdefg
  
  
  
  %
  

  fgets $B$O2~9TJ8;z$b%P%C%U%!$KFI$_9~$`!%(B $B$=$7$F(B puts $B$,J8;zNs$r=PNO$7$?8e$K2~9T$b=PNO$9$k;EMM$N$?$a!$2~9T$,(B2$B2s=PNO$5$l$F$7$^$$!$M>7W$J6u9T$,=P$F$7$^$&!%(B $B;HMQ$9$k$Y$-$G$O$J$$(B gets $B$O9TKv$N2~9TJ8;z$r%P%C%U%!$KFI$_9~$^$J$$$?$a!$$3$N$h$&$JLdBj$O@8$8$J$+$C$?(B($B$7$+$7(B1$B9T$NJ8;z?t$,%P%C%U%!$NBg$-$5$r1[$($F$7$^$&$H!$$b$C$HBg$-$JLdBj$,@8$8$F$7$^$&(B)$B!%(B

  $B0J2<$N(B$B%W%m%0%i%`(B$B$h$&$K(B puts $B$NBe$o$j$K(B fputs $B$r;HMQ$9$k$H!$(Bfputs $B$OC1$K%P%C%U%!Fb$NJ8;zNs$r=q$-=P$9$@$1$N;EMM$N$?$a!$>e5-$NLdBj$O$J$/$J$k!%(B

       1  #include <stdio.h>
       2  
       3  #define LINE_LEN        5
       4  
       5  main()
       6  {
       7          char    line_buf[LINE_LEN];
       8  
       9          while (fgets(line_buf, LINE_LEN, stdin) != NULL)
      10                  fputs(line_buf, stdout);
      11  }
  

  $BJ8;z!$J8;zNsA`:n%i%$%V%i%j(B

  $BJ8;zA`:n(B

  $BJ8;zA`:n$N%i%$%V%i%j4X?t$K$O!$0J2<$NBgJ8;zKt$O>.J8;z$XJQ49$9$k4X?t$H!$(B

  int toupper (int c);    /* $BBgJ8;z$XJQ49(B */
  int tolower (int c);    /* $B>.J8;z$XJQ49(B */
  

  $B0J2<$NJ8;z$N

  int isalnum (int c);    /* $B1Q;zKt$O?t;z!)(B */
  int isalpha (int c);    /* $B%"%k%U%!%Y%C%H!)(B */
  int isascii (int c);    /* $B%"%9%-!.J8;z!)(B */
  int isprint (int c);    /* $BI=<(2DG=!)!J%9%Z!<%9$r4^$`!K(B */
  int ispunct (int c);    /* $BI=<(2DG=!)!J%9%Z!<%9$H1Q?t;z$r=|$/!K(B */
  int isspace (int c);    /* $B6uGrJ8;z!)!J%9%Z!<%9!$%?%V!$2~9TJ8;z$J$I!K(B */
  int isupper (int c);    /* $BBgJ8;z!)(B */
  int isxdigit (int c);   /* 16$B?J?t$G$N?t;z!)!J(B0$B!A(B9, a$B!A(Bf, A$B!A(BF$B!K(B */
  

  $B0J2<$N(B$B%W%m%0%i%`(B$B$O>.J8;z$rBgJ8;z$X!$BgJ8;z$O>.J8;z$XJQ49$9$k!%(B o

       1  #include <stdio.h>
       2  #include <ctype.h>
       3
       4  main()
       5  {
       6          int     c;
       7
       8          while ((c = getchar()) != EOF) {
       9                  if (islower(c))
      10                          c = toupper(c);
      11                  else if (isupper(c))
      12                          c = tolower(c);
      13                  putchar(c);
      14          }
      15  }
  

  $B$3$l$r%3%s%Q%$%k

  % ./a.out 
  a
  A
  b
  B
  abcdefgABCDEFG
  ABCDEFGabcdefg
  
  %
  

  $BJ8;zNsA`:n(B

  string(3) $B$KJ8;zNsA`:n$N$?$a$N%i%$%V%i%j4X?t0lMw$,$N$C$F$$$k!J(Bman 3 string$B$GI=<(2DG=!K!%(B $BHf3SE*NI$/;H$o$l$k4X?t$K$D$$$F2r@b$9$k!%(B

  man 3 string $B$r8+$k$H!$4X?t$N%j%9%H$K4^$^$l$F(B

  #include <strings.h>
  #include <string.h>
  

  $B$H$G$F$$$k!%(B $BF1$8$3$H$O!$8DJL$N4X?t$N%^%K%e%"%k%Z!<%8$K$b$G$F$$$k!%(B $B$3$l$O!$$3$l$i$N4X?t$r;HMQ$9$k;~$K$O(B strings.h $BKt$O(B string.h $B$r%$%s%/%k!<%I$7$J$5$$$H$$$&0UL#$G$"$k!%(B $B;XDj$5$l$?%X%C%@%U%!%$%k$r%$%s%/%k!<%I$7$J$$$H!$%(%i!<$K$h$j%3%s%Q%$%k$G$-$J$$>l9g!$Kt$O4X?t$,@5>o$KF0:n$7$J$$>l9g$,$"$k!%(B

  $BJ8;zNs$ND9$5(B

  size_t strlen(const char *s);
  

  strlen $B$OJ8;zNs$ND9$5$rLa$jCM$H$7$FJV$9!%(B $BJ8;zNs$N=*C

  $B0J2<$N(B$B%W%m%0%i%`(B$B$O!$(B getchar, putchar $B$rMQ$$$?>.J8;z$rBgJ8;z$X!$BgJ8;z$O>.J8;z$XJQ49$9$k(B$B%W%m%0%i%`(B$B$r!$(Bfgets, fputs $B$rMQ$$$F9T$4$H$NF~=PNO$K$9$k$H!$J8;zNs$KBP$7!$BgJ8;z!$>.J8;z$NJQ49$r$9$k$h$&$K$J$k!%(B $BJ8;zNs$K4^$^$l$kJ8;z$r@hF,$+$i8+$F$$$/$?$a$K$O!$J8;zNs$ND9$5$,I,MW$K$J$k$?$a!$(Bstrlen $B$r;HMQ$9$k!%(B
  

       1  #include <stdio.h>
       2  #include <ctype.h>
       3  #include <string.h>
       4
       5  #define LINE_LEN        80
       6
       7  main()
       8  {
       9          int     i, len;
      10          char    line_buf[LINE_LEN];
      11          char    *p;
      12
      13          while (fgets(line_buf, LINE_LEN, stdin) != NULL) {
      14                  len = strlen(line_buf);
      15                  p = line_buf;
      16                  for (i = 0; i < len; i++, p++) {
      17                          if (islower(*p))
      18                                  *p = toupper(*p);
      19                          else if (isupper(*p))
      20                                  *p = tolower(*p);
      21                  }
      22                  fputs(line_buf, stdout);
      23          }
      24  }
  

  $B!J$BN}=,LdBj!J#1#3!K(B$B!K(B

  $BJ8;zNs$NHf3S(B

  int    strcmp(const char *s1, const char *s2);
  int    strncmp(const char *s1, const char *s2, size_t n);
  int    strcasecmp(const char *s1, const char *s2);
  int    strncasecmp(const char *s1, const char *s2, size_t n);
  

  $B$3$l$i$O(B2$B$D$NJ8;zNs(B s1 $B$H(B s2 $B$rHf3S$7!$(B

  $B>r7o(B			$B!!La$jCM(B
  s1	<	s2	$B!!(B0$B$h$j>.$5$$?t(B
  s1	==	s2	$B!!(B0
  s1	>	s2	$B!!(B0$B$h$jBg$-$$?t(B

  $B$H$$$&7k2L$rJV$9!%(B $BJ8;z$NBg>.4X78$O(BASCII$B%3!<%I(B$B$G$NBg>.$G$"$k!%(B

  strncmp, strncasecmp $B$O(B s1 $B$N@hF,(B n $BJ8;z$K$D$$$F$N$_!$Hf3S$r9T$&!%(B

  strcasecmp, strncasecmp $B$OBgJ8;z!$>.J8;z$r6hJL$;$:$K!JNc$($P(B A $B$H(B a $B$OF1$8$H$_$J$7$F!KHf3S$9$k!%(B

  $BJ8;z$dJ8;zNs$N8!:w(B

  char * strchr(const char *s, int c);
  char * strrchr(const char *s, int c);
  char * index(const char *s, int c);
  char * rindex(const char *s, int c);
  char * strstr(const char *haystack, const char *needle);
  

  strchr, index $B$O!$J8;zNs(B s $B$r@hF,$+$iC5$7$F:G=i$K(B c $B$NJ8;z$,8=$l$?$H$3$m$X$N%]%$%s%?$rJV$9!%(B

  strrchr, rindex $B$O!$J8;zNs(B s $B$r:G8eHx$+$iC5$7$F:G=i$K(B c $B$NJ8;z$,8=$l$?$H$3$m$X$N%]%$%s%?$rJV$9!%(B

  strstr $B$O!$J8;zNs(B haystack $B$r@hF,$+$iC5$7$F!$:G=i$K(B needle $B$,8+$D$+$C$?$H$3$m$X$N%]%$%s%?$rJV$9!%(B

  $B$I$l$b!$8+$D$+$i$J$+$C$?>l9g$O(B NULL $B$,La$jCM$K$J$k!%(B

  $B0J2<$N(B$B%W%m%0%i%`(B$B$O!$%U%!%$%k$X$N%Q%9$N9=@.MWAG$r@Z$j=P$7$F=PNO$9$k!%(B

       1  #include <stdio.h>
       2  #include <string.h>
       3  #include <sys/param.h>
       4
       5  main()
       6  {
       7          int     i;
       8          char    line_buf[MAXPATHLEN];
       9          char    *p, *np;
      10
      11          while (fgets(line_buf, MAXPATHLEN, stdin) != NULL) {
      12                  i = 0;
      13                  p = line_buf;
      14                  while ((np = index(p, '/')) != NULL) {
      15                          *np = '\0';
      16                          printf("%d: %s\n", i++, p);
      17                          p = np + 1;
      18                  }
      19                  printf("%d: %s\n", i, p);
      20          }
      21  }
  

  8$B9TL\$N(B MAXPATHLEN $B$O!$%7%9%F%`$GDj5A$5$l$F$$$k%Q%9L>$N:GBgD9$G$"$k!%(B MAXPATHLEN $B$O(B sys/param.h $B!J(B3$B9TL\!K$GDj5A$5$l$F$$$k!%(B $B$3$l$r%3%s%Q%$%k

  % ./a.out 
  dir0/dir1/dir2/dir3/file
  0: dir0
  1: dir1
  2: dir2
  3: dir3
  4: file
  
  
  %
  

  $BJ8;zNs$N%3%T!

  char * strcpy(char *dest, const char *src);
  char * strncpy(char *dest, const char *src, size_t n);
  

  strcpy $B$O!$(Bsrc $B$NJ8;zNs$r=*Cl9g!$(Bdest $B$N;D$j$NItJ,$O(B 0 $B$GKd$a$k!%(B

  char * strcat(char *dest, const char *src);
  char * strncat(char *dest, const char *src, size_t n);
  

  strcat $B$O!$(Bsrc $B$NJ8;zNs$r(B dest $B$NJ8;zNs$N8e$K!J(Bdest $B$N=*C

  strcat, strcpy $B$O!$%3%T!<@h$NBg$-$5$r;XDj$G$-$J$$$?$a!$%P%C%U%!%*!<%P!<%U%m!<$KBP$9$k@H

  $B$=$NB>$NJ8;zNsA`:n4X?t(B

  char * strdup(const char *s);                        /* $BJ8;zNs$NJ#@=(B */
  char * strfry(char *string);                         /* $BJ8;zNs$N%i%s%@%`2=(B */
  char * strsep(char **stringp, const char *delim);    /* $B%H!<%/%s$N@Z$j=P$7(B */
  char * strtok(char *s, const char *delim);           /* $B%H!<%/%s$X$NJ,2r(B */
  size_t strcspn(const char *s, const char *reject);   /* $BJ8;z%;%C%H$K4^$^$l$J$$J8;z?t(B */
  char * strpbrk(const char *s, const char *accept);   /* $BJ8;z%;%C%H$K4^$^$l$kJ8;z$N8!:w(B */
  size_t strspn(const char *s, const char *accept);    /* $BJ8;z%;%C%H$K4^$^$l$kJ8;z?t(B */
  int    strcoll(const char *s1, const char *s2);      /* $B%m%1!<%k$K4p$E$/J8;zNsHf3S(B */
  size_t strxfrm(char *dest, const char *src, size_t n);  /* $B%m%1!<%k$K4p$E$$$?J8;zNsJQ49(B */
  

  $BJ8;zNs$H?tCM$NJQ49(B

  getchar$B$d(Bfgets$B$G?t;z$rF~NO$H$7$F

  $B0J2<$OJ8;zNs$r?tCM$KJQ49$7$F$/$l$k%i%$%V%i%j4X?t$G$"$k!%(B sscanf $B$O(B scanf $B$HF1$8%P%C%U%!%*!<%P!<%U%m!<$KBP$9$k@H

  long int          strtol(const char *nptr, char **endptr, int base);
  unsigned long int strtoul(const char *nptr, char **endptr, int base);
  double            strtod(const char *nptr, char **endptr);
  long              atol(const char *nptr);
  int               atoi(const char *nptr);
  double            atof(const char *nptr);
  int               sscanf(const char *str, const char *format, ...);
  

  $B?tCM$rJ8;zNs$KJQ49$9$k%i%$%V%i%j4X?t$H$7$F(B sprintf, snprintf $B$,;HMQ$G$-$k!%(B sprintf $B$O!$Hs>o$KCm0U?<$/;HMQ$7$J$1$l$P!$%P%C%U%!%*!<%P!<%U%m!<$r5/$3$94m81$,$"$k!%(B snprintf $B$O=q$-=P$9:GBgJ8;z?t$r;XDj$G$-$k$N$G!$(Bsprintf $B$KBe$o$C$F>o$K(B snprintf $B$r;HMQ$9$Y$-$G$"$k!%(B $B$7$+$7(B snprintf $B$b!$8E$$(B UNIX $B$d(B Linux $B$G$O(B snprintf $B$O(B sprintf $B$r8F$S=P$7$F$$$k$@$1$N$3$H$,$"$j!$0BA4$G$O$J$$$3$H$,$"$k$N$GCm0U$,I,MW$G$"$k!%(B

  int sprintf(char *str, const char *format, ...);
  int snprintf(char *str, size_t size, const  char  *format, ...);
  

  $B%U%!%$%k%"%/%;%9(B

  $B%U%!%$%k%"%/%;%9$r$9$kJ}K!$K$O!$%7%9%F%`%3!<%k$rMQ$$$kJ}K!$H!$%i%$%V%i%j4X?t$rMQ$$$kJ}K!$,$"$k!%(B $B$I$A$i$K$;$h

  $B%i%$%V%i%j$rMQ$$$?%U%!%$%k$H$NF~=PNO(B

  $B%i%$%V%i%j$rMQ$$$F%U%!%$%k%"%/%;%9$r9T$&$?$a$K!$%U%!%$%k$r3+$-!$JD$8$k$?$a$K$O(B fopen, fclose $B$rMQ$$$k!%(B $BFI$_=q$-$N$?$a$K$O!$$BI8=`F~=PNO(B$B$G=R$Y$?4X?t$N$&$A!$@hF,$K(B f $B$,$D$$$F$$$k4X?t$,;HMQ$G$-$k!%(B $B0z?t$G;XDj$G$-$k(B FILE *stream $B$r!$(Bstdin, stdout $B$NBe$o$j$K!$(Bfopen $B$NLa$jCM$H$7$FF@$i$l$kCM$K$9$l$P$h$$!%(B $B%U%!%$%k$+$i$NF~=PNO$KJXMx$J$h$&$K(B fread, fwrite $B$H$$$&4X?t$bMQ0U$5$l$F$$$k!J$3$l$i$bI8=`F~=PNO$GMQ$$$k$3$H$,$G$-$k!K!%(B

  FILE * fopen(const char *path, const char *mode);
  int    fclose(FILE *stream);
  size_t fread(void  *ptr,  size_t size, size_t nmemb, FILE *stream);
  size_t fwrite(const void *ptr, size_t size, size_t  nmemb, FILE *stream);
  

  FILE$B9=B$BN(B

  $B%U%!%$%k$r3+$/$?$a$K;HMQ$9$k(B fopen $B$NLa$jCM$N7?$O(B FILE * $B!J(BFILE$B9=B$BN$X$N%]%$%s%?!K$G$"$k!%(B 1$BJ8;zF~NO$N(B fgetc $B$O!$FI$_9~$_@h$H$7$F0z?t$K(B FILE * $B7?$NJQ?t$r;XDj$7!$(B1$BJ8;z=PNO$N(B fputc $B$O0z?t$KJ8;z$NB>$K=q$-9~$_@h$H$7$F(B FILE * $B7?$NJQ?t$r;XDj$9$k!%(B

  $B$D$^$j!$%i%$%V%i%j$rMQ$$$F%U%!%$%k%"%/%;%9$r9T$&$?$a$K$O!$(BFILE$B9=B$BN$X$N%]%$%s%?!JDL>N!$%U%!%$%k%]%$%s%?!K$,!$%U%!%$%k$NBeM}?M$N$h$&$J$b$N$K$J$k!%(B

  FILE$B9=B$BN$K$O!$FI$_=q$-$7$F$$$k%U%!%$%k!$%U%!%$%k$KBP$75v$5$l$kA`:n!JFI$_9~$_!$=q$-9~$_!$Kt$ON>J}!K!$8=:_%U%!%$%k$N$I$NItJ,$r%"%/%;%9$7$F$$$k$N$+!$%(%i!<$O5/$-$F$$$J$$$+!$$J$I$N>pJs$r;}$D!%(B $B%U%!%$%k%]%$%s%?$O!$$3$N%G!<%?9=B$BN$X$N%]%$%s%?$K$J$C$F$*$j!$F~=PNO$K$"$?$C$F%U%!%$%k%]%$%s%?$r;XDj$9$k$3$H$G!$FI$_=q$-$r9T$&$3$H$,$G$-$k$h$&$K$J$C$F$$$k!%(B

  $B%U%!%$%k$N%3%T!<(B

  fgetc, fputc $B$rMQ$$$FI8=`F~NO$+$iFI$_9~$_!$I8=`=PNO$X=q$-=P$9(B$B%W%m%0%i%`(B$B$O!$(Bfopen, fclose $B$rA08e$KF~$l$k$3$H$G!$4JC1$K%U%!%$%k$N%3%T!<$r9T$&(B$B%W%m%0%i%`(B$B$K$J$k!%(B

       1  #include <stdio.h>
       2
       3  main()
       4  {
       5          int     c;
       6          FILE    *src, *dst;
       7
       8          src = fopen("src", "r");
       9          if (src == NULL) {
      10                  perror("src");
      11                  exit(1);
      12          }
      13
      14          dst = fopen("dst", "w+");
      15          if (dst == NULL) {
      16                  perror("dst");
      17                  fclose(src);
      18                  exit(1);
      19          }
      20
      21          while ((c = fgetc(src)) != EOF)
      22                  fputc(c, dst);
      23
      24          fclose(src);
      25          fclose(dst);
      26  }
  

  8$B9TL\$N(B fopen $B$G$O!$FI9~85$N%U%!%$%k$H$7$F(B "src" $B!$%*!<%W%s;~$N%b!<%I$H$7$F(B "r" $B$r;XDj$7$F$$$k!%(B $B%b!<%I$O!$%*!<%W%s$5$l$?%U%!%$%k$KBP$7$3$N8e5v$5$l$kA`:n!$5Z$S%*!<%W%s;~$N$I$3$+$iFI$_=q$-$,;O$^$k$+$r7hDj$9$k!%(B "r" $B$O!$%U%!%$%k$rFI$_9~$_$N$?$a$K%*!<%W%s$9$k$3$H$r0UL#$7!$%U%!%$%k$N@hF,$+$iFI$_9~$_$,;O$^$k!%(B

  14$B9TL\$N(B fopen $B$G$O!$=q$-9~$_@h$N%U%!%$%k$H$7$F(B "dst" $B!$%*!<%W%s;~$N%b!<%I$H$7$F(B "w+" $B$r;XDj$7$F$$$k!%(B "w+" $B$O!$FI$_=q$-$N$?$a$K%U%!%$%k$r%*!<%W%s$9$k$3$H$r0UL#$7!$%U%!%$%k$,B8:_$7$F$$$J$+$C$?>l9g$O?7$?$K:n$i$l!$B8:_$7$F$$$?>l9g$O%U%!%$%k$ND9$5$O(B 0 $B$K$5$l$k!%(B $B$^$?!$%U%!%$%k$NFI$_=q$-$O%U%!%$%k$N@hF,$+$i;O$^$k!%(B

  $BB>$K%b!<%I$H$7$F;XDj$G$-$kJ8;zNs$K$O!$(Br+, w, a, a+ $B!J$D$^$j(B rwa $B$NJ8;z$N$$$:$l$+!$Kt$O$=$l$K(B + $B$rIU$1$?$b$N!K$,$"$k!%(B $B$3$l$i$N0UL#$O(B FOPEN(3) $B$r;2>H!J(Bman fopen$B!K!%(B

  9$B!A(B12$B9TL\!$(B15$B!A(B19$B9TL\$O(B fopen $B$K<:GT$7$?;~$N=hM}$G$"$k!%(B $B$I$A$i$b4pK\E*$KF1$8$G!$(Bperror $B$K$h$j%(%i!<%a%C%;!<%8$r=PNO$7$?8e$K!$(Bexit $B$K$h$j%W%m%0%i%`$N\:Y$OMh=5$K3+@_$9$kM=Dj!%(B

  15$B!A(B19$B9TL\$N=hM}$K$O!$(B"src" $B%U%!%$%k$X$N%U%!%$%k%]%$%s%?$r%/%m!<%:$9$k(B fclose $B$,F~$C$F$$$k!J(B17$B9TL\!K!%(B $B%(%i!<=hM}$G(B exit $B$7$F$7$^$&>l9g$O!$A4$F$N%U%!%$%k$O<+F0E*$K%/%m!<%:$5$l!$NN0h$b3+J|$5$l$F$7$^$&$?$a!$$3$N(B fclose $B$Ol9g$K$O!$F1;~$K%*!<%W%s$G$-$k%U%!%$%k$K$O@)8B$,$"$j!$$^$?%a%b%j%j!<%/$,5/$-$J$$$h$&$K$9$k$?$a$K$b!$4XO"$9$k%U%!%$%k%]%$%s%?$r3N

  main$B4X?t$N0z?t(B

  $B%U%!%$%k$N%3%T!<$J$I$N%3%^%s%I$N%W%m%0%i%`$r:n$k;~$K$O!$%3%T!<$9$k%U%!%$%kL>$r%3%^%s%I9T$N0z?t$H$7$FEO$;$k$HJXMx$G$"$k!%(B $B$3$N$h$&$J%W%m%0%i%`5/F0;~$N0z?t$O!$(Bmain $B4X?t$X$N0z?t$H$7$FEO$5$l$k!%(B $B0J2<$N%W%m%0%i%`$O!$%3%^%s%I9T$N0z?t$r=PNO$9$k!%(B

       1  #include <stdio.h>
       2
       3  main(int argc, char *argv[])
       4  {
       5          int     i;
       6
       7          for (i = 0; i < argc; i++)
       8                  puts(argv[i]);
       9  }
  

  $B$3$l$r%3%s%Q%$%k

  % ./a.out src dst 
  ./a.out
  src
  dst
  %
  

  $B>e5-%W%m%0%i%`$N(B3$B9TL\$N(B main $B4X?t$N0z?t$H$7$F(B argc, argv $B$,;XDj$5$l$F$*$j!$(B argc $B$O(B int $B7?!$(Bargv $B$O(B char * $B7?$NG[Ns!J(Bchar $B7?$X$N%]%$%s%?$r3JG<$9$kG[Ns!K$G$"$k!%(B argc $B$O(B argument count$B!$(Bargv $B$O(B argument vector $B$NN,$G$"$k!%(B main $B4X?t$N0z?t$NL>A0$O(B argc, argv $B$G$"$kI,MW@-$O$J$$$,!$47NcE*$K(B argc, argv $B$,;H$o$l$F$-$F$*$j!$$3$NL>A0$G;H$&$3$H$,%W%m%0%i%`$N$o$+$j$d$9$5$NE@$G$bK>$^$7$$!%(B

  argc $B$K$O%3%^%s%I9T$NJ8;zNs$N8D?t$,F~$k!J%3%^%s%IL>!\0z?t!K!%(B $B>e5-$N

  argv $B$O!$%3%^%s%I9T$NJ8;zNs$=$l$>$l$X$N%]%$%s%?$r3JG<$7$?G[Ns$G$"$k!%(B $B2e5-$N$NJ8;zNs(B "./a.out" $B!$(B argv[1] $B$O:G=i$N0z?t(B "src" $B!$(B argv[2] $B$O

  $B%i%$%V%i%j4X?t$rMQ$$$F%U%!%$%k$N%3%T!<$r9T$&(B$B%W%m%0%i%`(B$B$r!$%3%T!<$9$k%U%!%$%kL>$r%3%^%s%I9T$N0z?t$H$7$FEO$;$k$h$&$K$9$k$H$B%W%m%0%i%`(B$B$K$J$k!%(B

       1  #include <stdio.h>
       2
       3  main(int argc, char *argv[])
       4  {
       5          int     c;
       6          FILE    *src, *dst;
       7
       8          if (argc != 3) {
       9                  printf("Usage: %s from_file to_file\n", argv[0]);
      10                  exit(1);
      11          }
      12
      13          src = fopen(argv[1], "r");
      14          if (src == NULL) {
      15                  perror(argv[1]);
      16                  exit(1);
      17          }
      18
      19          dst = fopen(argv[2], "w+");
      20          if (dst == NULL) {
      21                  perror(argv[2]);
      22                  fclose(src);
      23                  exit(1);
      24          }
      25
      26          while ((c = fgetc(src)) != EOF)
      27                  fputc(c, dst);
      28
      29          fclose(src);
      30          fclose(dst);
      31  }
  

  argc, argv $B$r2rl9g$O!$0z?t$N?t$r%A%'%C%/$9$k$3$H$,Bg@Z$G$"$k!%(B $B>e5-$N%W%m%0%i%`$G$O(B 8$B!A(B11$B9TL\$G!$0z?t$N?t$,(B 3 $B$G$J$1$l$P!$$=$N%W%m%0%i%`$N;H$$J}$rI=<($7!$%W%m%0%i%`$r=*N;$9$k$h$&$K$7$F$$$k!%(B

  $B$3$l$r%3%s%Q%$%k

  % ./a.out 
  Usage: ./a.out from_file to_file
  % ./a.out src_file dst 
  src_file: No such file or directory
  % ./a.out src dst 
  %
  

  $B%7%9%F%`%3!<%k$rMQ$$$?%U%!%$%k$H$NF~=PNO(B

  $B%7%9%F%`%3!<%k$rMQ$$$F%U%!%$%k%"%/%;%9$r9T$&$?$a$K!$%U%!%$%k$r3+$-!$JD$8$k$?$a$K$O(B open, close $B$rMQ$$$k!%(B $BFI$_=q$-$N$?$a$N%7%9%F%`%3!<%k$O(B read, write $B$rMQ$$$k!%(B $B%i%$%V%i%j4X?t$H0[$J$j!$(Bread, write $B0J30$K$OFI$_=q$-$N$?$a$N%7%9%F%`%3!<%k$O$J$$!%(B

  int     open(const char *pathname, int flags);
  int     open(const char *pathname, int flags, mode_t mode);
  int     close(int fd);
  ssize_t read(int fd, void *buf, size_t count);
  ssize_t write(int fd, const void *buf, size_t count);
  

  $B%U%!%$%k%"%/%;%9$N$?$a$N%7%9%F%`%3!<%k$O>e5-$N(B open, close, read, write $B$G$"$k!%(B $B%i%$%V%i%j4X?t$b%U%!%$%k%"%/%;%9$r9T$&$?$a$K!$:G=*E*$K$O%7%9%F%`%3!<%k$r;HMQ$9$k!%(B $B=>$C$F!$(Bfopen $B$O(B open $B$r8F$S!$(Bfclose $B$O(B close $B$r8F$V!%(B $BF~NO$N$?$a$N(B getchar, fgetc, fgets, fread $B$O(B read $B$r8F$S!$=PNO$N$?$a$N(B putchar, fputc, fputs, fwrite $B$O(B write $B$r8F$V!%(B

  $B%U%!%$%k%G%#%9%/%j%W%?(B

  fopen $B$O(B FILE $B9=B$BN$X$N%]%$%s%?$rJV$7!$$=$N8e%*!<%W%s$7$?%U%!%$%k$X$N%"%/%;%9$N$?$a$K$O$=$N%]%$%s%?$rMQ$$$k!%(B open $B$O%*!<%W%s$K@.8y$9$k$H(B 0 $B0J>e$N@0?t$rJV$9!%(B $B$=$N@0?t$O!$%U%!%$%k%G%#%9%/%j%W%?!J%U%!%$%k5-=R;R!K$H8F$P$l$k!%(B $B%7%9%F%`%3!<%k$rMQ$$$F%U%!%$%k%"%/%;%9$r9T$&>l9g$O!$(Bopen $B$K$h$j%U%!%$%k$r%*!<%W%s$7$?8e$O!$La$jCM$N%U%!%$%k%G%#%9%/%j%W%?$r;XDj$9$k$3$H$K$h$j!$$=$N%U%!%$%k$KBP$7FI$_=q$-$r(B read, write $B$rMQ$$$F9T$&$3$H$,$G$-$k!%(B $B%U%!%$%k%"%/%;%9$,=*N;$7$?$i!$%U%!%$%k%G%#%9%/%j%W%?$r0z?t$K(B close $B$r8F$V$3$H$G!$$=$N%U%!%$%k$r%/%m!<%:$G$-$k!%(B

  $B$"$k%W%m%;%9$,0l;~$K%*!<%W%s$G$-$k%U%!%$%k$N?t!J%U%!%$%k%G%#%9%/%j%W%?$N:GBgCM!K$O@)8B$5$l$F$$$k!%(B $B@N$N(B UNIX $B$G$OHs>o$K>/$J$+$C$?$,!$8=:_$O$+$J$jB?$/$N%U%!%$%k$r0l;~$K%*!<%W%s$9$k$3$H$,$G$-$k!%(B Linux $B$G$O(B /proc/sys/fs/file-max $B$K@_Dj$5$l$F$$$kCM$,:GBgCM$G$"$k$,!$DL>o$N%W%m%;%9$O(B 1024 $B$K@_Dj$5$l$F$$$k!%(B

  $BI8=`F~=PNO$N%U%!%$%k%G%#%9%/%j%W%?(B

  $B%i%$%V%i%j4X?t$K$h$kF~=PNO$b7k6I$O%7%9%F%`%3!<%k$r8F$S=P$9$3$H$G

  $BI8=`F~=PNO$N$?$a$N%U%!%$%k%G%#%9%/%j%W%?$H$7$F(B 0, 1, 2 $B$,3d$jEv$F$i$l$F$$$k!%(B 0 $B$,I8=`F~NO!$(B1 $B$,I8=`=PNO!$(B2 $B$,I8=`%(%i!<=PNO$KBP1~$9$k!%(B $B$3$l$i(B3$B$D$N%U%!%$%k%G%#%9%/%j%W%?$O!$%W%m%0%i%`$,uBV$K$J$C$F$$$k!%(B

  $B%U%!%$%k$N%3%T!<(B

  $B%i%$%V%i%j4X?t$rMQ$$$F%U%!%$%k$N%3%T!<$r9T$&(B$B%W%m%0%i%`(B$B$r!$%7%9%F%`%3!<%k$rMQ$$$k$h$&$K=q$-49$($k$H0J2<$N(B$B%W%m%0%i%`(B$B$N$h$&$K$J$k!%(B

       1  #include <stdio.h>
       2  #include <fcntl.h>
       3
       4  main()
       5  {
       6          char    c;
       7          int     src, dst;
       8          int     count;
       9
      10          src = open("src", O_RDONLY);
      11          if (src < 0) {
      12                  perror("src");
      13                  exit(1);
      14          }
      15
      16          dst = open("dst", O_WRONLY | O_CREAT | O_TRUNC, 0666);
      17          if (dst < 0) {
      18                  perror("dst");
      19                  close(src);
      20                  exit(1);
      21          }
      22
      23          while ((count = read(src, &c, 1)) > 0) {
      24                  if (write(dst, &c, count) < 0) {
      25                          perror("write");
      26                          exit(1);
      27                  }
      28          }
      29
      30          if (count < 0) {
      31                  perror("read");
      32                  exit(1);
      33          }
      34
      35          close(src);
      36          close(dst);
      37  }
  

  $B%W%m%0%i%`$NN.$l$O!$%i%$%V%i%j4X?t$rMQ$$$?>l9g$HF1$8$G$"$k!%(B open $B$X$N0z?t$O!$%*!<%W%s$7$?$$%U%!%$%kL>$H!$%U%!%$%k$r%*!<%W%s$9$k%b!<%I$G$"$k!%(B O_RDONLY $B$OFI$_9~$_$N$_!$(BO_WRONLY $B$O=q$-9~$_$N$_$G$"$k!%(B $BFI$_=q$-$N>l9g$O(B O_RDWR $B$r;XDj$9$k!%(B O_RDONLY, O_WRONLY, O_RDWR $B$H0l=o$K@_Dj$G$-$k%b!<%I$,$$$/$D$+$"$k!%(B O_CREAT $B$,%;%C%H$5$l$F$$$k$H!$%U%!%$%k$,B8:_$7$J$+$C$?>l9g$O:n@.$9$k!%(B O_TRUNC $B$,%;%C%H$5$l$F$$$k$H!$%U%!%$%k$,4{$KB8:_$7$?>l9g$O%U%!%$%k$ND9$5$O(B 0 $B$K$5$l$k!%(B $B%b!<%I$K(B O_CREAT $B$,4^$^$l$k>l9g$O!$%U%!%$%k$,:n$i$l$?>l9g$K@_Dj$9$k%Q!<%_%C%7%g%s$,(B3$BHVL\$N0z?t$K$J$k!%(B $B

  read $B$OFI$_9~$a$k:GBg%P%$%H?t!$(Bwrite $B$O=q$-9~$a$k:GBg%P%$%H?t$r;XDj$9$k$,!$$=$l$>$l;XDj$5$l$?$@$1$N:GBg%P%$%H?t$rFI$_9~$_Kt$O=q$-9~$_$G$-$k$H$O8B$i$J$$!%(B $B

  read, write $B$G;XDj$9$kFI$_=q$-$N:GBg%P%$%H?t$O!$Bg$-$$$[$&$,(B read, write $B%7%9%F%`%3!<%k$N8F$S=P$7$H%3%T!<$N2s?t$,>/$J$/$F$9$`$N$G!$$h$j8zN(E*$G$"$k!%(B $B$D$^$j>e5-$N%W%m%0%i%`$N$h$&$K(B 1 $B$H$9$k$N$O!$Hs>o$K8zN($,0-$$!%(B $BDL>o(B 1024, 4096, 8192 $B$J$I$NCM$,MQ$$$i$l$k$,!$:G$b8zN($NNI$$CM$OF~=PNO@h$N%G%P%$%9!$%G%P%$%9$r@)8f$9$k%3%s%H%m!<%i!$%a%b%j$NNL$J$I$K0MB8$9$k!%!J"*(B$BN}=,LdBj!J#1#6!K(B$B!K(B

  $B%i%$%V%i%j$H%7%9%F%`%3!<%k$N:.:_(B

  $BF10l$N%U%!%$%k$KBP$9$k%"%/%;%9$r%i%$%V%i%j$H%7%9%F%`%3!<%k$G:.$<$F9T$&$3$H$O!$%W%m%0%i%_%s%0>e$O2DG=$G$O$"$k$,!$7k2L$,$*$+$7$/$J$k2DG=@-$,$"$k$N$G!$Hr$1$k$Y$-$G$"$k!%(B $B%i%$%V%i%j4X?t$G$NF~=PNO$O!$(B1$BJ8;zC10L$NF~=PNO$b8zN($h$/9T$($k$h$&$K!$F~=PNO%G!<%?$r0l;~E*$KC_$($k%P%C%U%!%j%s%0$r$9$k$3$H$G!$%7%9%F%`%3!<%k$N2s?t$r8:$i$7$F$$$k!%(B $B:.$<$F;H$&$H!$%P%C%U%!%j%s%0$5$l$?%G!<%?$H$N@09g@-$,

  $B$I$&$7$F$b!$$I$A$i$+$+$i$I$A$i$+$XJQ49$7$?$$;~$K$O!$0J2<$N4X?t$r;HMQ$9$k$3$H$,$G$-$k!%(B fileno, fdopen $B$O!$==J,$J%F%9%H$r$9$k$J$I2?$r$7$F$$$k$N$+M}2r$9$k$h$&Cm0U$7$F;HMQ$9$Y$-$G!$0B0W$K;HMQ$9$Y$-$G$O$J$$!%(B

  fflush $B$O!$>e5-$NL\E*$H$O4X78$J$/!$%P%C%U%!%j%s%0$5$l$?%G!<%?$r%U%i%C%7%e$7$?$$;~$K$b;HMQ$G$-$k!%(B

  int  fileno(FILE *stream);            /* FILE$B9=B$BN$N%U%!%$%k%G%#%9%/%j%W%?$rJV$9(B */
  FILE *fdopen(int fildes, char *mode); /* $B%U%!%$%k%G%#%9%/%j%W%?$+$i(BFILE$B9=B$BN$r:n$k(B */
  int  fflush( FILE *stream);           /* $B%P%C%U%!%j%s%0$5$l$?%G!<%?$r%U%i%C%7%e(B */
  

  $B%P%C%U%!%*!<%P!<%U%m!<(B

  $B%P%C%U%!%*!<%P!<%U%m!<$O%W%m%0%i%`$Nh$Ch$C

  $B%P%C%U%!%*!<%P!<%U%m!<$,$I$&$7$F5/$3$k$N$+M}2r$9$k$?$a$K$O!$%W%m%;%9$,

  $B2o!$:G$b2<0L%"%I%l%9$K5!3#8lL?Na$,F~$C$?%F%-%9%HNN0h$,CV$+$l$k!%(B $B$=$N>e$K%G!<%?NN0h$,CV$+$l$k!%(B $B%G!<%?NN0h$H$OJL$K!$4X?t8F$S=P$7;~$NLa$j%"%I%l%9!J%j%?!<%s%"%I%l%9!K$d4X?t$N%m!<%+%kJQ?t$,3JG<$5$l$k%9%?%C%/NN0h$,$"$k!%(B $B%G!<%?NN0h$O%G!<%?3d$jEv$F$,5/$3$k$?$S$K>e0L%"%I%l%9$K8~$+$C$F?-$S$F$$$/!%(B $B%9%?%C%/NN0h$O5U$K!$4X?t8F$S=P$7$,5/$3$k$?$S$K2<0L%"%I%l%9$K8~$+$C$F?-$S$F$$$/!%(B

  $B%9%?%C%/NN0h$r$h$j>\:Y$K?^<($9$k$H2

  $B%9%?%C%/%U%l!<%`Cf$N%m!<%+%kJQ?t$KG[Ns$,4^$^$l$F$$$k$H!$G[Ns$NE:;z$,>.$5$$$[$&$,2<0L%"%I%l%9$K$"$j!$Bg$-$$$[$&$,>e0L%"%I%l%9$K$/$k!%(B $B>e$N?^$G(B buf $B$,%]%$%s%?$H$7$FNc$($P(B gets $B$KEO$5$l$k$H!$(Bbuf[0] $B$+$i>e0L%"%I%l%9$K8~$+$C$F=q$-9~$^$l$F$$$/!%(B 64$BJ8;z0J>e$NJ8;z$,=q$-9~$^$l$k$H!$(Bbuf[63] $B$rD6$($F=q$-9~$^$l!$(Bbuf $B$H$7$F3d$jEv$F$i$l$?NN0h$rD6$($F=q$-9~$^$l$F$7$^$&$3$H$K$J$k!%(B $B$5$i$K=q$-9~$^$l$k$H!$%j%?!<%s%"%I%l%9$b=q$-49$($i$l$F$7$^$&!%(B $B%9%?%C%/NN0h$K$&$^$/%W%m%0%i%`$r=q$-9~$_!$%j%?!<%s%"%I%l%9$r$=$N%W%m%0%i%`$N3+;O%"%I%l%9$K@_Dj$7$F$"$2$k$H!$4X?t$,La$k;~$K=q$-9~$s$@%W%m%0%i%`$,

  $B$3$N$h$&$J967bJ}K!$r%9%?%C%/%9%^%C%7%s%0(B (stack smashing) $B$H8F$V!%(B

  $BN}=,LdBj(B

  $BN}=,LdBj!J#1#1!K(B

  $BJ8;zNs$N$H$3$m$K$"$k(B$B%W%m%0%i%`(B$B$rJQ99$7!$J8;zNsDj?t$NFbMF$rJQ99$9$k$H!$%;%0%a%s%F!<%7%g%s%U%)%k%H$,H/@8$9$k$3$H$r3N$+$a$h!%(B

  $B$^$?!$(Bcc $B$N%*%W%7%g%s$K(B -fwritable-strings $B$rM?$($k$HJ8;zNsDj?t$NFbMF$rJQ99$,2DG=$K$J$k$3$H$b3N$+$a$h!%(B

  $BN}=,LdBj!J#1#2!K(B

  $BI8=`F~=PNO$rMQ$$$k%i%$%V%i%j4X?t$N$H$3$m$K$"$k(B fgets$B!$(Bputs $B$rMQ$$$?(B$B%W%m%0%i%`(B$B$N(B LINE_LEN $B$r(B 5 $B$K$7$F!$%3%s%Q%$%k

  % ./a.out 
  1234567890
  1234
  5678
  90
  
  abcdefg
  abcd
  efg
  
  
  %
  

  $BN}=,LdBj!J#1#3!K(B

  strlen $B$N$H$3$m$K$"$kJ8;zNs$K4^$^$l$k>.J8;z$rBgJ8;z$X!$BgJ8;z$O>.J8;z$XJQ49$9$k(B$B%W%m%0%i%`(B$B$r!$(Bstrlen $B$r;HMQ$;$:!$=*C

  $BN}=,LdBj!J#1#4!K(B

  $BJ8;z!$J8;zNs$N8!:w$N$H$3$m$K$"$k(B$B%W%m%0%i%`(B$B$O!$@hF,$K(B / $B$,$"$k>l9g$r$&$^$/07$($:!$

  % ./a.out 
  /dir1/dir2/dir3/file
  0:
  1: dir1
  2: dir2
  3: dir3
  4: file
  
  
  %
  

  $BN}=,LdBj!J#1#5!K(B

  $BN}=,LdBj!J#1#4!K$Ge$2$?(B$B%W%m%0%i%`(B$B$O!$KvHx$,(B / $B$G=*$o$k>l9g$b$&$^$/07$($J$$!%(B $BKvHx$N(B / $B$OL5;k$9$k$h$&$K!$JQ99$;$h!%(B

  % ./a.out 
  dir0/dir2/dir3/
  0: dir0
  1: dir2
  2: dir3
  3:
  
  
  %
  

  $BN}=,LdBj!J#1#6!K(B

  $B%7%9%F%`%3!<%k$rMQ$$$F%U%!%$%k%3%T!<$r9T$&(B$B%W%m%0%i%`(B$B$N%3%T!<85$N%U%!%$%k$r%5%$%:$,Bg$-$J$b$N$KJQ99$7!$%P%C%U%!%5%$%:$r$$$m$$$mJQ$($F

  $B%W%m%0%i%`$N

  % time ./a.out 
  1.050u 5.870s 0:06.96 99.4%     0+0k 0+0io 77pf+0w
  %
  

  $BC5n$9$k$3$H!*!*(B

  $BN}=,LdBj!J#1#7!K(B

  $B%i%$%V%i%j$rMQ$$$F%U%!%$%k%3%T!<$r9T$&(B$B%W%m%0%i%`(B$B$G!$%3%T!<85$N%U%!%$%k$r%5%$%:$,Bg$-$J$b$N$r;XDj$7!$(Bfgets, fputs $BKt$O(B fread, fwrite $B$rMQ$$$FF~=PNO$r9T$$!$%P%C%U%!%5%$%:$r$$$m$$$mJQ$($F

  $B7k2L$O!$%7%9%F%`%3!<%k$N>l9g$HHf3S$7$F$I$N$h$&$K$J$C$?$@$m$&$+!)(B $B0c$$$K$D$$$F!$9M;!$;$h!%(B

  $BN}=,LdBj!J#1#8!K(B

  $B0J2<$N$h$&$K!$%7%'%k$N$h$&$K(B1$B9TF~NO$r$HF~NO$N%j%@%$%l%/%7%g%s5-9f!V(B<$B!W$,$"$l$P$=$N8e$N%U%!%$%kL>$rI=<($7!$$=$&$G$J$1$l$PF~NO$H$7$F(B console $B$H=PNO$9$k%W%m%0%i%`$r:n$j$J$5$$!%(B $BF~NO9T$O!$%3%^%s%IL>$@$1!$$^$?$O!V%3%^%s%IL>(B < $B%U%!%$%kL>!W!J(B< $B$NA08e$K%9%Z!<%9(B1$B$D!K$H$$$&7A<0$@$1$KBP1~$9$l$P$h$$!%(B

  % ./a.out 
  command
  command name: command
  input: console
  command < file
  command name: command
  input: file
  %
  

  $BN}=,LdBj!J#1#9!K(B

  $BN}=,LdBj!J#1#8!K$N%W%m%0%i%`$rJQ99$7!$=PNO$N%j%@%$%l%/%7%g%s5-9f!V(B>$B!W$K$bBP1~$G$-$k$h$&$K$;$h!%(B $B%j%@%$%l%/%7%g%s5-9f$N=P8==g=x$OF~NO!V(B<$B!W$N8e$K=PNO!V(B>$B!W$,8=$l$k>l9g$K$N$_BP1~$9$l$P$h$$!%(B

  $BN}=,LdBj!J#2#0!K(B

  $BN}=,LdBj!J#1#9!K$N%W%m%0%i%`$rJQ99$7!$F1$8%j%@%$%l%/%7%g%s5-9f$,J#?t=P$F$-$?$i!$%(%i!<%a%C%;!<%8$,=PNO$5$l$k$h$&$K$;$h!%(B

  $BN}=,LdBj!J#2#1!K(B

  $BN}=,LdBj!J#2#0!K$N%W%m%0%i%`$rJQ99$7!$F1$8%j%@%$%l%/%7%g%s5-9f$,=P8==g=x$,JQ$o$C$F$bBP1~$G$-$k$h$&$K$7$J$5$$!%(B

  $BN}=,LdBj!J#2#2!K(B

  $BN}=,LdBj!J#2#1!K$N%W%m%0%i%`$rJQ99$7!$%9%Z!<%9$,%3%^%s%I!$%j%@%$%l%/%7%g%s5-9f!$%U%!%$%kL>$N<~$j$KF~$C$F$$$J$/$F$b!$$^$?$OJ#?t8DF~$C$F$$$F$b!$F1$8$h$&$K=hM}$G$-$k$h$&$K$7$J$5$$!%(B