string(3C)          (C Programming Language Utilities)           string(3C)


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

   SYNOPSIS
         #include <string.h>

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

         char *strdup (const char *s1);

         char *strncat (char *s1, const char *s2, sizet n);

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

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

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

         char *strncpy (char *s1, const char *s2, sizet n);

         sizet strlen (const char *s);

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

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

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

         sizet strspn (const char *s1, const char *s2);

         sizet strcspn (const char *s1, const char *s2);

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

         char *strstr (const char *s1, const char *s2);

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

         strcat appends a copy of string s2, including the terminating null
         character, to the end of string s1.  strncat appends at most n
         characters.  Each returns a pointer to the null-terminated result.
         The initial character of s2 overrides the null character at the end
         of s1.




   7/91                                                                 Page 1

   string(3C)          (C Programming Language Utilities)           string(3C)


         strcmp compares its arguments and returns an integer less than, equal
         to, or greater than 0, based upon whether s1 is lexicographically
         less than, equal to, or greater than s2.  strncmp makes the same
         comparison but looks at at most n characters.  Characters following a
         null character are not compared.

         strcpy copies string s2 to s1 including the terminating null
         character, 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 will not be null-
         terminated if the length of s2 is n or more.  Each function returns
         s1.

         strdup returns a pointer to a new string which is a duplicate of the
         string pointed to by s1.  The space for the new string is obtained
         using malloc(3C).  If the new string can not be created, a NULL
         pointer is returned.

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

         strchr (or strrchr) returns a pointer to the first (last) occurrence
         of c (converted to a char) in string s, or a NULL pointer if c does
         not occur in the string.  The null character terminating 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 (or 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 will
         have written a null character into s1 immediately following the
         returned token. The function keeps track of its position in the
         string between separate calls, so that subsequent calls (which must
         be made with the first argument a NULL pointer) will work through the
         string s1 immediately following that token.  In this way subsequent
         calls will work through the string s1 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.

         strstr locates the first occurrence in string s1 of the sequence of
         characters (excluding the terminating null character) in string s2.
         strstr returns a pointer to the located string, or a null pointer if
         the string is not found. If s2 points to a string with zero length


   Page 2                                                                 7/91

   string(3C)          (C Programming Language Utilities)           string(3C)


         (i.e., the string ""), the function returns s1.

   SEE ALSO
         malloc(3C), setlocale(3C), strxfrm(3C).

   NOTES
         All of these functions assume the default locale ``C.''  For some
         locales, strxfrm should be applied to the strings before they are
         passed to the functions.












































   7/91                                                                 Page 3