STRLEN(3) Library Functions Manual STRLEN(3)

strlen strnlen — get length of fixed size string

#include <string.h>

size_t strlen(const char *s);
[CX] size_t strnlen(const char *s, size_t maxlen);

For strlen (): [CX] 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.

[CX] 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.

[CX] 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 example sets the maximum length of and 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(3)

XBD <string.h>

First released in Issue 1. Derived from Issue 1 of the SVID.

The RETURN VALUE section is updated to indicate that strlen () returns the length of s, and not s itself as was previously stated.

The strnlen () function is added from The Open Group Technical Standard, 2006, Extended API Set Part 1.

January 1, 2008 posix.fail