NAME

string - string operations

SYNOPSIS

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 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, c;

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

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

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

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

DESCRIPTION

These functions operate on null-terminated strings. They do not check for overflow of any receiving string.

strcat appends a copy of string s2 to the end of string s1. strncat copies at most n characters. Both return a pointer to the null-terminated result.

strcmp compares its arguments and returns an integer greater than, equal to, or less than 0, according as s1 is lexicographically greater than, equal to, or less than s2. strncmp makes the same comparison but looks at most n characters.

strcpy copies string s2 to s1, stopping after the null character has been moved. strncpy copies exactly n characters, truncating or null-paadding s2; the target may not be null-terminated if the length of s2 is n or more. Both return s1.

strlen returns the number of non-null characters in s.

strchr (strrchr) returns a pointer to the first (last) occurence of character c in string s, or NULL 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 NULL if no character from s2 exists in s1.

strtok considers the string s1 to consist of a sequence of zero or more text tokens seperated 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. Subsequent calls with zero for the first argument, will work through the string s1 in this way until no tokens remain. The separator string s2 may be different from call to call. When no tokens remain in s1, a NULL is returned.

BUGS

strcmp uses native character comparison, which is signed on PDP-11s, unsigned on other machines.

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.