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     string(3C)                                             string(3C)



     NAME
          strcat, strncat, strcmp, strncmp, strcpy, strncpy, strlen,
          strchr,  strrchr,  strpbrk, strspn, strcspn, strtok - string
          operations

     SYNOPSIS
          #include <string.h>

          char *strcat(s1, s2)
          char *s1, *s2;

          char *strncat(s1, s2, n)
          char *s1, *s2;
          int n;

          int strcmp(s1, s2)
          char *s1, *s2;

          int strncmp(s1, s2, n)
          char *s1, *s2;
          int n;

          char *strcpy(s1, s2)
          char *s1, *s2;

          char *strncpy(s1, s2, n)
          char *s1, *s2;
          int n;

          int strlen(s)
          char *s;

          char *strchr(s, c)
          char *s;
          int c;

          char *strrchr(s, c)
          char *s;
          int c;

          char *strpbrk(s1, s2)
          char *s1, *s2;

          int strspn(s1, s2)
          char *s1, *s2;

          int strcspn(s1, s2)
          char *s1, *s2;

          char *strtok(s1, s2)
          char *s1, *s2;




     April, 1990                                                     1

     string(3C)                                             string(3C)



     DESCRIPTION
          The arguments s1, s2, and s point to strings (arrays of
          characters terminated by a null character).  The functions
          strcat, strncat, strcpy, and strncpy all alter s1.  These
          functions do not check for overflow of the array pointed to
          by s1.

          strcat appends a copy of string s2 to the end of string s1.
          strncat appends at most n characters.  Each function returns
          a pointer to the null-terminated result.

          strcmp performs a lexicographical comparison of its argu-
          ments and returns an integer less than, equal to, or greater
          than 0, when s1 is less than, equal to, or greater than s2,
          respectively.  strncmp makes the same comparison but looks
          at a maximum of n characters.

          strcpy copies string s2 to string s1, stopping after the
          null character has been copied.  strncpy copies exactly n
          characters, truncating s2 or adding null characters to s1 if
          necessary.  The result is not null-terminated if the length
          of s2 is n or more.  Each function returns s1.

          strlen returns the number of characters in s, not including
          the terminating null character.

          strchr (strrchr) returns a pointer to the first (last) oc-
          currence of character c in string s, or a NULL pointer if c
          does not occur in the string.  The null character terminat-
          ing a string is considered to be part of the string.

          strpbrk returns a pointer to the first occurrence in string
          s1 of any character from string s2, or a NULL pointer if no
          character from s2 exists in s1.

          strspn (strcspn) returns the length of the initial segment
          of string s1 which consists entirely of characters from (not
          from) string s2.

          strtok considers the string s1 to consist of a sequence of
          zero or more text tokens separated by spans of one or more
          characters from the separator string s2.  The first call
          (with pointer s1 specified) returns a pointer to the first
          character of the first token, and writes a null character
          into s1 immediately following the returned token.  The func-
          tion keeps track of its position in the string between
          separate calls, so that on subsequent calls (which must be
          made with a NULL pointer as the first argument) it works
          through the string s1 immediately following that token.
          This can be continued until no tokens remain.  The separator
          string s2 may be different from call to call.  When no token
          remains in s1, a NULL pointer is returned.



     2                                                     April, 1990

     string(3C)                                             string(3C)



     NOTES
          For user convenience, some of these functions are declared
          in the optional <string.h> header file.

     BUGS
          strcmp uses native character comparison.  Thus the sign of
          the value returned when one of the characters has its high-
          order bit set is implementation-dependent.

          All string movement is performed character by character
          starting at the left.  Thus overlapping moves toward the
          left will work as expected, but overlapping moves to the
          right may yield surprises.










































     April, 1990                                                     3