strspn.c

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/***************************************************************************//**
 @file strspn.c
 
 @brief Defines the strspn function
*******************************************************************************/
#include <string.h>
 
/*******************************************************************************
 strspn
*//**
 @brief Find the length of the span of characters in s2 in s1
 @param *s1 String being searched
 @param *s2 String of characters in the span being found
 
 The strspn function computes the length of the maximum initial segment of
 the string pointed to by s1 which consists entirely of characters from the
 string pointed to by s2.
 
 @return Length of the segment
*******************************************************************************/
size_t
strspn(const char *s1, const char *s2)
{
 size_t len = 0;
 
 if (!s1 || !s2)
 {
 return 0;
 }
 
 while (*s1 &&
 strchr(s2, *s1++))
 {
 len++;
 }
 
 return len;
}