C/wctype.h/iswblank
int iswblank(wint_t ch) vs isblank()
#include <stdio.h>
#include <wctype.h>
int main(void)
{
int wc;
for (wc=0; wc <= 0xFF; wc++) {
printf("%3d", wc);
printf(" %#4x ", wc);
printf("%3s", iswblank(wc) ? "AN" : " ");
putchar("\n");
}
}