strspn man page


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.

strspn — get length of a substring


#include <string.h>

size_t strspn(const char *s1, const char *s2);


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 strspn() function shall compute the length (in bytes) of the maximum initial segment of the string pointed to by s1 which consists entirely of bytes from the string pointed to by s2.

Return Value

The strspn() function shall return the computed length; no return value is reserved to indicate an error.


No errors are defined.

The following sections are informative.

See Also


The Base Definitions volume of POSIX.1‐2008, <string.h>