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STRLEN(3P) POSIX Programmer's Manual STRLEN(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
strlen, strnlen — get length of fixed size string
#include <string.h>
size_t strlen(const char *s);
size_t strnlen(const char *s, size_t maxlen);
For strlen(): 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 POSIX.1‐2008 defers to the ISO C standard.
The strlen() function shall compute the number of bytes in the string
to which s points, not including the terminating NUL character.
The strnlen() function shall compute the smaller of the number of
bytes in the array to which s points, not including the terminating
NUL character, or the value of the maxlen argument. The strnlen()
function shall never examine more than maxlen bytes of the array
pointed to by s.
The strlen() function shall return the length of s; no return value
shall be reserved to indicate an error.
The strnlen() function shall return an integer containing the smaller
of either the length of the string pointed to by s or maxlen.
No errors are defined.
The following sections are informative.
Getting String Lengths
The following example sets the maximum length of key and data by
using strlen() to get the lengths of those strings.
#include <string.h>
...
struct element {
char *key;
char *data;
};
...
char *key, *data;
int len;
*keylength = *datalength = 0;
...
if ((len = strlen(key)) > *keylength)
*keylength = len;
if ((len = strlen(data)) > *datalength)
*datalength = len;
...
None.
None.
None.
wcslen(3p)
The Base Definitions volume of POSIX.1‐2008, string.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 STRLEN(3P)
Pages that refer to this page: string.h(0p), localeconv(3p), strnlen(3p), wcslen(3p)