STRCAT(2)                                               STRCAT(2)

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

     SYNOPSIS
          #include <u.h>
          #include <libc.h>

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

          char* strncat(char *s1, char *s2, long n)

          int   strcmp(char *s1, char *s2)

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

          int   cistrcmp(char *s1, char *s2)

          int   cistrncmp(char *s1, char *s2, long n)

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

          char* strecpy(char *s1, char *es1, char *s2)

          char* strncpy(char *s1, char *s2, long n)

          long  strlen(char *s)

          char* strchr(char *s, char c)

          char* strrchr(char *s, char c)

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

          long  strspn(char *s1, char *s2)

          long  strcspn(char *s1, char *s2)

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

          char* strdup(char *s)

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

          char* cistrstr(char *s1, char *s2)

     DESCRIPTION
          The arguments s1, s2 and s point to null-terminated strings.

     STRCAT(2)                                               STRCAT(2)

          The functions strcat, strncat, strcpy, strecpy, and strncpy
          all alter s1. Strcat and strcpy 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 bytes.  Each returns a pointer to
          the null-terminated result.

          Strcmp compares its arguments and returns an integer less
          than, equal to, or greater than 0, according as s1 is lexi-
          cographically less than, equal to, or greater than s2.
          Strncmp makes the same comparison but examines at most n
          bytes.  Cistrcmp and cistrncmp ignore ASCII case distinc-
          tions when comparing strings.  The comparisons are made with
          unsigned bytes.

          Strcpy copies string s2 to s1, stopping after the null byte
          has been copied.  Strncpy copies exactly n bytes, truncating
          s2 or adding null bytes to s1 if necessary.  The result will
          not be null-terminated if the length of s2 is n or more.
          Each function returns s1.

          Strecpy copies bytes until a null byte has been copied, but
          writes no bytes beyond es1. If any bytes are copied, s1 is
          terminated by a null byte, and a pointer to that byte is
          returned.  Otherwise, the original s1 is returned.

          Strlen returns the number of bytes in s, not including the
          terminating null byte.

          Strchr (strrchr) returns a pointer to the first (last)
          occurrence of byte c in string s, or `0' if c does not occur
          in the string.  The null byte terminating a string is con-
          sidered to be part of the string.

          Strpbrk returns a pointer to the first occurrence in string
          s1 of any byte from string s2, `0' if no byte from s2 exists
          in s1.

          Strspn (strcspn) returns the length of the initial segment
          of string s1 which consists entirely of bytes 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
          bytes from the separator string s2. The first call, with
          pointer s1 specified, returns a pointer to the first byte of
          the first token, and will have written a null byte into s1
          immediately following the returned token.  The function
          keeps track of its position in the string between separate
          calls; subsequent calls, signified by s1 being `0', will
          work through the string s1 immediately following that token.

     STRCAT(2)                                               STRCAT(2)

          The separator string s2 may be different from call to call.
          When no token remains in s1, `0' is returned.

          Strdup returns a pointer to a distinct copy of the null-
          terminated string s in space obtained from malloc(2) or `0'
          if no space can be obtained.

          Strstr returns a pointer to the first occurrence of s2 as a
          substring of s1, or 0 if there is none.  If s2 is the null
          string, strstr returns s1. Cistrstr operates analogously,
          but ignores ASCII case differences when comparing strings.

     SOURCE
          All these routines have portable C implementations in
          /sys/src/libc/port.  Many also have machine-dependent assem-
          bly language implementations in /sys/src/libc/$objtype.

     SEE ALSO
          memory(2), rune(2), runestrcat(2), string(2)

     BUGS
          These routines know nothing about UTF.  Use the routines in
          rune(2) as appropriate.  Note, however, that the definition
          of UTF guarantees that strcmp compares UTF strings cor-
          rectly.

          The outcome of overlapping moves varies among implementa-
          tions.