isprint

From cppreference.com
< c‎ | string‎ | byte
Defined in header <ctype.h>
int isprint( int ch );

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.

The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF.

Parameters

ch - character to classify

Return value

Non-zero value if the character can be printed, zero otherwise.