| 
STRSPN(3) | 
Library Functions Manual | 
STRSPN(3) | 
NAME
 strspn — span a string
LIBRARY
 Standard C Library (libc, -lc)
SYNOPSIS
 #include <string.h>
size_t
strspn(const char *s, const char *charset);
 
DESCRIPTION
 The strspn() function spans the initial part of the nul-terminated string s as long as the characters from s occur in string charset.
RETURN VALUES
 The strspn() function returns the number of characters spanned.
EXAMPLES
 The following call to 
strspn() will return 3, since the first three characters of string 
s are part of string 
charset:
char *s = "foobar"; 
char *charset = "of"; 
size_t span; 
 
span = strspn(s, charset);
 
STANDARDS
 The strspn() function conforms to ANSI X3.159-1989 (“ANSI C89”).