cpp/string/byte/isgraph

Checks if the given character is graphic (has a graphical representation) as classified by the currently installed C locale. In the default C locale, the following characters are graphic:


 * digits
 * uppercase letters
 * lowercase letters
 * punctuation characters

The behavior is undefined if the value of is not representable as  and is not equal to.

Return value
Non-zero value if the character has a graphical representation character, zero otherwise.