.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved .TH "STRTOK" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual" .\" strtok .SH NAME strtok, strtok_r \- split string into tokens .SH SYNOPSIS .LP \fB#include .br .sp char *strtok(char *restrict\fP \fIs1\fP\fB, const char *restrict\fP \fIs2\fP\fB); .br \fP .LP \fBchar *strtok_r(char *restrict\fP \fIs\fP\fB, const char *restrict\fP \fIsep\fP\fB, .br \ \ \ \ \ \ char **restrict\fP \fIlasts\fP\fB); \fP \fB .br \fP .SH DESCRIPTION .LP For \fIstrtok\fP(): The functionality described on this reference page is aligned with the ISO\ C standard. Any conflict between the requirements described here and the ISO\ C standard is unintentional. This volume of IEEE\ Std\ 1003.1-2001 defers to the ISO\ C standard. .LP A sequence of calls to \fIstrtok\fP() breaks the string pointed to by \fIs1\fP into a sequence of tokens, each of which is delimited by a byte from the string pointed to by \fIs2\fP. The first call in the sequence has \fIs1\fP as its first argument, and is followed by calls with a null pointer as their first argument. The separator string pointed to by \fIs2\fP may be different from call to call. .LP The first call in the sequence searches the string pointed to by \fIs1\fP for the first byte that is \fInot\fP contained in the current separator string pointed to by \fIs2\fP. If no such byte is found, then there are no tokens in the string pointed to by \fIs1\fP and \fIstrtok\fP() shall return a null pointer. If such a byte is found, it is the start of the first token. .LP The \fIstrtok\fP() function then searches from there for a byte that \fIis\fP contained in the current separator string. If no such byte is found, the current token extends to the end of the string pointed to by \fIs1\fP, and subsequent searches for a token shall return a null pointer. If such a byte is found, it is overwritten by a null byte, which terminates the current token. The \fIstrtok\fP() function saves a pointer to the following byte, from which the next search for a token shall start. .LP Each subsequent call, with a null pointer as the value of the first argument, starts searching from the saved pointer and behaves as described above. .LP The implementation shall behave as if no function defined in this volume of IEEE\ Std\ 1003.1-2001 calls \fIstrtok\fP(). .LP The \fIstrtok\fP() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe. .LP The \fIstrtok_r\fP() function considers the null-terminated string \fIs\fP as a sequence of zero or more text tokens separated by spans of one or more characters from the separator string \fIsep\fP. The argument \fIlasts\fP points to a user-provided pointer which points to stored information necessary for \fIstrtok_r\fP() to continue scanning the same string. .LP In the first call to \fIstrtok_r\fP(), \fIs\fP points to a null-terminated string, \fIsep\fP to a null-terminated string of separator characters, and the value pointed to by \fIlasts\fP is ignored. The \fIstrtok_r\fP() function shall return a pointer to the first character of the first token, write a null character into \fIs\fP immediately following the returned token, and update the pointer to which \fIlasts\fP points. .LP In subsequent calls, \fIs\fP is a NULL pointer and \fIlasts\fP shall be unchanged from the previous call so that subsequent calls shall move through the string \fIs\fP, returning successive tokens until no tokens remain. The separator string \fIsep\fP may be different from call to call. When no token remains in \fIs\fP, a NULL pointer shall be returned. .SH RETURN VALUE .LP Upon successful completion, \fIstrtok\fP() shall return a pointer to the first byte of a token. Otherwise, if there is no token, \fIstrtok\fP() shall return a null pointer. .LP The \fIstrtok_r\fP() function shall return a pointer to the token found, or a NULL pointer when no token is found. .SH ERRORS .LP No errors are defined. .LP \fIThe following sections are informative.\fP .SH EXAMPLES .SS Searching for Word Separators .LP The following example searches for tokens separated by s. .sp .RS .nf \fB#include \&... char *token; char *line = "LINE TO BE SEPARATED"; char *search = " "; .sp /* Token will point to "LINE". */ token = strtok(line, search); .sp /* Token will point to "TO". */ token = strtok(NULL, search); \fP .fi .RE .SS Breaking a Line .LP The following example uses \fIstrtok\fP() to break a line into two character strings separated by any combination of s, s, or s. .sp .RS .nf \fB#include \&... struct element { char *key; char *data; }; \&... char line[LINE_MAX]; char *key, *data; \&... key = strtok(line, " \\n"); data = strtok(NULL, " \\n"); \&... \fP .fi .RE .SH APPLICATION USAGE .LP The \fIstrtok_r\fP() function is thread-safe and stores its state in a user-supplied buffer instead of possibly using a static data area that may be overwritten by an unrelated call from another thread. .SH RATIONALE .LP The \fIstrtok\fP() function searches for a separator string within a larger string. It returns a pointer to the last substring between separator strings. This function uses static storage to keep track of the current string position between calls. The new function, \fIstrtok_r\fP(), takes an additional argument, \fIlasts\fP, to keep track of the current position in the string. .SH FUTURE DIRECTIONS .LP None. .SH SEE ALSO .LP The Base Definitions volume of IEEE\ Std\ 1003.1-2001, \fI\fP .SH COPYRIGHT Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .