C's ctype.h prototype

1. Introduction of prototypes

#include <ctype.h>

2. Character Judgment function

Name of function	Judgment set to (true)
Isalnum ()	Letters or numbers
Isalpha ()	Letters
Isblank ()	White space characters (spaces, tabs, line breaks) or any localized characters that are specified as whitespace
Iscntrl ()	Control character
Isgraph ()	All printable characters except for whitespace
Islower ()	lowercase letters
Isprint ()	printable characters
Ispunct ()	Punctuation (except spaces and alphanumeric printable characters)
Isspace ()	Whitespace characters: spaces | wrapping | paper | return | vertical TAB | Horizontal tab | or localized definition character
Isupper ()	Capital
Isxdigit ()	hexadecimal numeric characters
ToLower ()	Returns the lowercase character if it is an uppercase character, otherwise, returns the original argument
ToUpper	If it is lowercase, returns the uppercase character or returns the original argument

eg

#include <stdio.h><ctype.h>int main (void) {    int  CH;    Puts (" Please enter a number ")    ; = GetChar ();     if (IsDigit (CH)) //          putchar (CH);     Else          printf (" not \ n");}

C's ctype.h prototype