| .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" |
| .\" Permission is granted to make and distribute verbatim copies of this |
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| .\" Permission is granted to copy and distribute modified versions of this |
| .\" manual under the conditions for verbatim copying, provided that the |
| .\" entire resulting derived work is distributed under the terms of a |
| .\" permission notice identical to this one. |
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| .\" Since the Linux kernel and libraries are constantly changing, this |
| .\" manual page may be incorrect or out-of-date. The author(s) assume no |
| .\" responsibility for errors or omissions, or for damages resulting from |
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| .\" Formatted or processed versions of this manual, if unaccompanied by |
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| .\" References consulted: |
| .\" Linux libc source code |
| .\" 386BSD man pages |
| .\" Modified Sat Jul 24 18:50:48 1993 by Rik Faith (faith@cs.unc.edu) |
| .\" Interchanged `needle' and `haystack'; added history, aeb, 980113. |
| .TH MEMMEM 3 1998-01-13 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| memmem \- locate a substring |
| .SH SYNOPSIS |
| .nf |
| .B #define _GNU_SOURCE |
| .br |
| .B #include <string.h> |
| .sp |
| .BI "void *memmem(const void *" haystack ", size_t " haystacklen , |
| .in +\w'void *memmem('u |
| .BI "const void *" needle ", size_t " needlelen ); |
| .in |
| .fi |
| .SH DESCRIPTION |
| The \fBmemmem\fP() function finds the start of the first occurrence |
| of the substring \fIneedle\fP of length \fIneedlelen\fP in the memory |
| area \fIhaystack\fP of length \fIhaystacklen\fP. |
| .SH "RETURN VALUE" |
| The \fBmemmem\fP() function returns a pointer to the beginning of the |
| substring, or NULL if the substring is not found. |
| .SH "CONFORMING TO" |
| This function is a GNU extension. |
| .SH BUGS |
| This function was broken in Linux libraries up to and including libc 5.0.9; |
| there the `needle' and `haystack' arguments were interchanged, |
| and a pointer to the end of the first occurrence of \fIneedle\fP |
| was returned. Since libc 5.0.9 is still widely used, this is a |
| dangerous function to use. |
| .br |
| Both old and new libc's have the bug that if \fIneedle\fP is empty |
| \fIhaystack\fP-1 (instead of \fIhaystack\fP) is returned. |
| And glibc 2.0 makes it worse, and returns a pointer to the |
| last byte of `haystack'. This is fixed in glibc 2.1. |
| .SH "SEE ALSO" |
| .BR strstr (3) |