NAME

strcat, strcmp, strncmp, strcpy, strncpy, strlen, strchr, strrchr, strdup, strstr − string operations

SYNOPSIS

char∗strcat(char ∗s1, char ∗s2)

intstrcmp(char ∗s1, char ∗s2)

intstrncmp(char ∗s1, char ∗s2, long n)

char∗strcpy(char ∗s1, char ∗s2)

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

longstrlen(char ∗s)

char∗strchr(char ∗s, char c)

char∗strrchr(char ∗s, char c)

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, strcpy, and ­strncpy all alter s1. These functions 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, and 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.  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 ­0 if ­c does not occur in the string.  The null byte terminating a string is considered to be part of the string. 

­Strdup returns a pointer to a distinct copy of the null-terminated string ­s in space obtained from malloc(10.2) 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.

SOURCE

­/kern/str∗.c
­/kern/str∗-objtype.c
­/lib9/strdup.c

SEE ALSO

memory(10.2), rune(10.2)

BUGS

These routines know nothing about UTF.  Use the routines in rune(10.2) as appropriate. Note, however, that the definition of UTF guarantees that ­strcmp compares UTF strings correctly. 

The outcome of overlapping moves varies among implementations. 

Note the absence of ANSI C’s strncat, strpbrk, strspn, strcspn and strtok, but the presence of strdup.

Plan 9  —  June 07, 2000