strcspn Function

Calculate the number of consecutive characters at the beginning of a string that are not contained in a set of characters.

Include

<string.h>

Prototype

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

Arguments

s1

pointer to the string to be searched

s2

pointer to characters to search for

Return Value

Returns the length of the segment in s1 not containing characters found in s2.

Remarks

This function will determine the number of consecutive characters from the beginning of s1 that are not contained in s2.

Example

#include <string.h>
#include <stdio.h>

int main(void)
{
  char str1[20] = "hello";
  char str2[20] = "aeiou";
  char str3[20] = "animal";
  char str4[20] = "xyz";
  int res;

  res = strcspn(str1, str2);
  printf("strcspn(\"%s\", \"%s\") = %d\n", 
          str1, str2, res);

  res = strcspn(str3, str2);
  printf("strcspn(\"%s\", \"%s\") = %d\n", 
          str3, str2, res);

  res = strcspn(str3, str4);
  printf("strcspn(\"%s\", \"%s\") = %d\n", 
          str3, str4, res);
}

Example Output

strcspn("hello", "aeiou") = 1
strcspn("animal", "aeiou") = 0
strcspn("animal", "xyz") = 6

Example Explanation

In the first result, e is in s2 so it stops counting after h.

In the second result, a is in s2.

In the third result, none of the characters of s1 are in s2 so all characters are counted.