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STRCAT(2)                     System Calls Manual                    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.  The func‐
       tions strcat, strncat, strcpy, strecpy, and strncpy all alter s1.  Str‐
       cat 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 lexicographically 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
       distinctions  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 if c does not occur in  the  string.   The  null
       byte terminating a string is considered to be part of the string.

       Strpbrk  returns  a pointer to the first occurrence in string s1 of any
       byte from string s2, 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 func‐
       tion keeps track of its position in the string between separate  calls;
       subsequent calls, signified by s1 being will work through the string s1
       immediately following that token.  The separator string s2 may be  dif‐
       ferent from call to call.  When no token remains in s1, is returned.

       Strdup  returns  a  pointer  to  a distinct copy of the null-terminated
       string s in space obtained  from  malloc(2)  or  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 assembly 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 correctly.

       The outcome of overlapping moves varies among implementations.



                                                                     STRCAT(2)