STRCAT(2)							System Calls Manual							 STRCAT(2)

NAME

       strcat, strncat, strcmp, strncmp, strcpy, strncpy, strlen, strchr, strrchr, strpbrk, strspn, strcspn, strtok, strdup, strstr - string oper-
       ations

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)

       char* strcpy(char *s1, 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)

DESCRIPTION

       The arguments s1, s2 and s point to null-terminated strings.  The functions strcat, strncat, strcpy, and strncpy all alter s1.  These func-
       tions 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-termi-
       nated 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.  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.

       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  sepa-
       rator  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 will work through the string s1 immediately following that token.  The separator string s2
       may be different 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.

   Alef
       The routines strcspn, strpbrk, and strspn are not provided in Alef.

SOURCE

       All these routines have portable C implementations in /sys/src/libc/port.  Many also have machine-dependent assembly  language  implementa-
       tions in /sys/src/libc/$objtype.

SEE ALSO

       memory(2), rune(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)