isprint
Header: <ctype.h>
Checks if the given character can be printed, i.e. it is either a number (0123456789), an uppercase letter (ABCDEFGHIJKLMNOPQRSTUVWXYZ), a lowercase letter (abcdefghijklmnopqrstuvwxyz), a punctuation character(!"#$%&’()*+,-./:;<=>?@[]^_`{|}~), or space, or any character classified as printable by the current C locale.
# Declarations
int isprint( int ch );
# Parameters
ch: character to classify
# Return value
Non-zero value if the character can be printed, zero otherwise.
# Example
#include <stdio.h>
#include <ctype.h>
#include <locale.h>
int main(void)
{
unsigned char c = '\xa0'; // the non-breaking space in ISO-8859-1
printf("In the default C locale, \\xa0 is %sprintable\n", isprint(c)?"":"not ");
setlocale(LC_ALL, "en_GB.iso88591");
printf("In ISO-8859-1 locale, \\xa0 is %sprintable\n", isprint(c)?"":"not ");
}