strcspn

Returns the length of the maximum initial segment of the null-terminated byte string pointed to by dest, that consists of only the characters not found in the null-terminated byte string pointed to by src.

The behavior is undefined if either dest or src is not a pointer to a null-terminated byte string.

[edit] Parameters

[edit] Return value

The length of the maximum initial segment that contains only characters not found in the null-terminated byte string pointed to by src

[edit] Notes

The function name stands for "complementary span" because the function searches for characters not found in src, that is the complement of src.

[edit] Example

#include <string.h>
#include <stdio.h>
 
int main(void)
{
 const char *string = "abcde312$#@";
 const char *invalid = "*$#";
 
 size_t valid_len = strcspn(string, invalid);
 if(valid_len != strlen (string))
 printf ("'%s' contains invalid chars starting at position %zu\n",
 string, valid_len);
}

'abcde312$#@' contains invalid chars starting at position 8

[edit] References

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