strtok_r(3C)
NAME
string, strcasecmp, strncasecmp, strcat, strncat, strlcat,
strchr, strrchr, strcmp, strncmp, strcpy, strncpy, strlcpy,
strcspn, strspn, strdup, strlen, strpbrk, strstr, strtok,
strtok_r - string operations
SYNOPSIS
#include <strings.h>
int strcasecmp(const char *s1, const char *s2);
int strncasecmp(const char *s1, const char *s2, size_t n);
#include <string.h>
char *strcat(char *s1, const char *s2);
char *strncat(char *s1, const char *s2, size_t n);
size_t strlcat(char *dst, const char *src, size_t dstsize);
char *strchr(const char *s, int c);
char *strrchr(const char *s, int c);
int strcmp(const char *s1, const char *s2);
int strncmp(const char *s1, const char *s2, size_t n);
char *strcpy(char *s1, const char *s2);
char *strncpy(char *s1, const char *s2, size_t n);
size_t strlcpy(char *dst, const char *src, size_t dstsize);
size_t strcspn(const char *s1, const char *s2);
size_t strspn(const char *s1, const char *s2);
char *strdup(const char *s1);
size_t strlen(const char *s);
char *strpbrk(const char *s1, const char *s2);
char *strstr(const char *s1, const char *s2);
char *strtok(char *s1, const char *s2);
char *strtok_r(char *s1, const char *s2, char **lasts);
ISO C++
#include <string.h>
const char *strchr(const char *s, int c);
const char *strpbrk(const char *s1, const char *s2);
const char *strrchr(const char *s, int c);
const char *strstr(const char *s1, const char *s2);
#include <cstring>
char *std::strchr(char *s, int c);
char *std::strpbrk(char *s1, const char *s2);
char *std::strrchr(char *s, int c);
char *std::strstr(char *s1, const char *s2);
DESCRIPTION
The arguments s, s1, and s2 point to strings (arrays of
characters terminated by a null character). The strcat(),
strncat(), strlcat(), strcpy(), strncpy(), strlcpy(),
strtok(), and strtok_r() functions all alter their first
argument. These functions do not check for overflow of the
array pointed to by the first argument.
strcasecmp(), strncasecmp()
The strcasecmp() and strncasecmp() functions are case-
insensitive versions of strcmp() and strncmp() respec-
tively, described below. They assume the ASCII character
set and ignore differences in case when comparing lower and
upper case characters.
strcat(), strncat(), strlcat()
The strcat() function appends a copy of string s2, including
the terminating null character, to the end of string s1. The
strncat() function appends at most n characters. Each
returns a pointer to the null-terminated result. The initial
character of s2 overrides the null character at the end of
s1.
The strlcat() function appends at most (dstsize-
strlen(dst)-1) characters of src to dst (dstsize being the
size of the string buffer dst). If the string pointed to by
dst contains a null-terminated string that fits into dstsize
bytes when strlcat() is called, the string pointed to by dst
will be a null-terminated string that fits in dstsize bytes
(including the terminating null character) when it com-
pletes, and the initial character of src will override the
null character at the end of dst. If the string pointed to
by dst is longer than dstsize bytes when strlcat() is
called, the string pointed to by dst will not be changed.
The function returns the sum the of lengths of the two
strings strlen(dst)+strlen(src). Buffer overflow can be
checked as follows:
if (strlcat(dst, src, dstsize) >= dstsize)
return -1;
strchr(), strrchr()
The strchr() function returns a pointer to the first
occurrence of c (converted to a char) in string s, or a
null pointer if c does not occur in the string. The
strrchr() function returns a pointer to the last occurrence
of c. The null character terminating a string is considered
to be part of the string.
strcmp(), strncmp()
The strcmp() function compares two strings byte-by-byte,
according to the ordering of your machine's character set.
The function returns an integer greater than, equal to, or
less than 0, if the string pointed to by s1 is greater
than, equal to, or less than the string pointed to by s2
respectively. The sign of a non-zero return value is deter-
mined by the sign of the difference between the values of
the first pair of bytes that differ in the strings being
compared. The strncmp() function makes the same comparison
but looks at a maximum of n bytes. Bytes following a null
byte are not compared.
strcpy(), strncpy(), strlcpy()
The strcpy() function copies string s2 to s1, including the
terminating null character, stopping after the null charac-
ter has been copied. The strncpy() function copies exactly n
bytes, truncating s2 or adding null characters to s1 if
necessary. The result will not be null-terminated if the
length of s2 is n or more. Each function returns s1.
The strlcpy() function copies at most dstsize-1 characters
(dstsize being the size of the string buffer dst) from src
to dst, truncating src if necessary. The result is always
null-terminated. The function returns strlen(src). Buffer
overflow can be checked as follows:
if (strlcpy(dst, src, dstsize) >= dstsize)
return -1;
strcspn(), strspn()
The strcspn() function returns the length of the initial
segment of string s1 that consists entirely of characters
not from string s2. The strspn() function returns the length
of the initial segment of string s1 that consists entirely
of characters from string s2.
strdup()
The strdup() function returns a pointer to a new string that
is a duplicate of the string pointed to by s1. The returned
pointer can be passed to free(). The space for the new
string is obtained using malloc(3C). If the new string can-
not be created, a null pointer is returned and errno may be
set to ENOMEM to indicate that the storage space available
is insufficient.
strlen()
The strlen() function returns the number of bytes in s, not
including the terminating null character.
strpbrk()
The strpbrk() function returns a pointer to the first
occurrence in string s1 of any character from string s2, or
a null pointer if no character from s2 exists in s1.
strstr()
The strstr() function locates the first occurrence of the
string s2 (excluding the terminating null character) in
string s1 and returns a pointer to the located string, or a
null pointer if the string is not found. If s2 points to a
string with zero length (that is, the string ""), the func-
tion returns s1.
strtok()
The strtok() function can be used to break the string
pointed to by s1 into a sequence of tokens, each of which is
delimited by one or more characters from the string pointed
to by s2. The strtok() function considers the string s1 to
consist of a sequence of zero or more text tokens separated
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. The function keeps track of its position
in the string between separate calls, so that subsequent
calls (which must be made with the first argument being a
null pointer) will work through the string s1 immediately
following that token. In this way subsequent calls will work
through the string s1 until no tokens remain. The separator
string s2 may be different from call to call. When no token
remains in s1, a null pointer is returned.
strtok_r()
The strtok_r() function has the same functionality as
strtok() except that a pointer to a string placeholder lasts
must be supplied by the caller. The lasts pointer is to
keep track of the next substring in which to search for the
next token.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| MT-Level | See NOTES below. |
|_____________________________|_____________________________|
SEE ALSO
malloc(3C), setlocale(3C), strxfrm(3C), attributes(5)
NOTES
When compiling multithreaded applications, the _REENTRANT
flag must be defined on the compile line. This flag should
only be used in multithreaded applications.
All of these functions assume the default locale ``C.'' For
some locales, strxfrm() should be applied to the strings
before they are passed to the functions.
The strcasecmp(), strcat(), strchr(), strcmp(), strcpy(),
strcspn(), strdup(), strlen(), strncasecmp(), strncat(),
strncmp(), strncpy(), strpbrk(), strrchr(), strspn(), and
strstr() functions are MT-Safe in multithreaded applica-
tions.
The strtok() function is Unsafe in multithreaded applica-
tions. The strtok_r() function should be used instead.
Man(1) output converted with
man2html