Compute the length of a string
Synopsis:
#include <string.h>
size_t strlen( const char * s );
Arguments:
- s
- The string whose length you want to calculate.
Library:
libc
Use the -l c option to
qcc
to link against this library.
This library is usually included automatically.
Description:
The strlen() function computes
the length of the string pointed to by s.
Returns:
The number of characters that precede the terminating null character.
Examples:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main( void )
{
printf( "%d\n", strlen( "Howdy" ) );
printf( "%d\n", strlen( "Hello world\n" ) );
printf( "%d\n", strlen( "" ) );
return EXIT_SUCCESS;
}
produces the output:
5
12
0
Environment variables:
- LIBC_STRINGS
- On ARMv7 targets, you can use this environment variable to select the implementation for this function.
The value is one of the following:
- cortex_a9 — optimized for the ARM Cortex-A9 processor;
assumes that no unaligned access is supported.
- cortex_a9_aligned — optimized for ARM Cortex-A9; requires that unaligned memory access
be enabled on the platform.
If memory access is misaligned, this implementation falls back to the NEON version.
- cortex_a9_neon — optimized for ARM Cortex-A9 using NEON.
- generic — the default.
- krait — optimized for the Qualcomm Krait CPU.
- krait_neon — optimized for Qualcomm Krait using NEON.
Processes that register ISRs shouldn't use the NEON versions.
Classification:
ANSI,
POSIX 1003.1
Safety: |
|
Cancellation point |
No |
Interrupt handler |
Yes |
Signal handler |
Yes |
Thread |
Yes |