strcat, strncat, strcmp, strncmp, strcpy, strncpy, strlen, strchr, strrchr, strpbrk, str-
spn, strcspn, strtok, strdup, strstr - string operations
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)
The arguments s1, s2 and s point to null-terminated strings. The functions strcat, strn-
cat, 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. 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. The comparisons are made with
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 sepa-
rated 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, signi-
fied 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
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.
The routines strcspn, strpbrk, and strspn are not provided in Alef.
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.
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.