C Language Strings strspn and strcspn
Example
Given a string, strspn calculates the length of the initial substring (span) consisting solely of a specific list of characters. strcspn is similar, except it calculates the length of the initial substring consisting of any characters except those listed:
/*
Provided a string of "tokens" delimited by "separators", print the tokens along
with the token separators that get skipped.
*/
#include <stdio.h>
#include <string.h>
int main(void)
{
const char sepchars[] = ",.;!?";
char foo[] = ";ball call,.fall gall hall!?.,";
char *s;
int n;
for (s = foo; *s != 0; /*empty*/) {
/* Get the number of token separator characters. */
n = (int)strspn(s, sepchars);
if (n > 0)
printf("skipping separators: << %.*s >> (length=%d)\n", n, s, n);
/* Actually skip the separators now. */
s += n;
/* Get the number of token (non-separator) characters. */
n = (int)strcspn(s, sepchars);
if (n > 0)
printf("token found: << %.*s >> (length=%d)\n", n, s, n);
/* Skip the token now. */
s += n;
}
printf("== token list exhausted ==\n");
return 0;
}
Analogous functions using wide-character strings are wcsspn and wcscspn; they're used the same way.
