Usage and example of C library function isgraph()

C Standard Library <ctype.h>

　The isgraph() function is used to detect whether a character is a graphic character.

Characters with graphic representation are known graphic characters.

isgraph() checks if a character is a graphic character. If the parameter passed to isgraph() is a graphic character, it will return a non-zero integer. If not, it returns 0.

This function is inctype.h 　Defined in header file　

Function prototype of isgraph()

int isgraph(int argument);

The isgraph() function takes a single parameter and returns an integer.

When a character is passed as a parameter, the corresponding ASCII value of the character is passed, not the character itself.

Example1Check graphic characters

#include <stdio.h>
#include <ctype.h>
int main()
{
　　　　char c;
　　　　int result;
　　　　c = ' ';
　　　　result = isgraph(c);
　　　　printf("When %c is passed to isgraph() = %d
", c, result);
　　　　c = '\n';
　　　　result = isgraph(c);
　　　　printf("When %c is passed to isgraph() = %d
", c, result);
　　　　c = '9';
　　　　result = isgraph(c);
　　　　printf("When %c is passed to isgraph() = %d
", c, result);

Output result

when          passed to isgraph() = 0
when　
　when passed to isgraph() = 0
when　9　when passed to isgraph() =　1

Example #2Print all graphic characters

#include <stdio.h>
#include <ctype.h>
int main()
{
　　　　int i;
　　　　printf("All graphic characters in C programming are: 
");
　　　　for (i = 0; i <=127;++i)
　　　　{
　　　　　　　　if (isgraph(i) != 0)
　　　　　　　　　　　　printf("%c ", i);
　　　　}
　　　　return 0;
}

Output result

All graphic characters in C programming are:　
! " # $ % & ' ( )　*　+　,　-　.　/　0　1　2　3　4　5　6　7　8　9　: ; < = > ? @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ \ ] ^ _ ` a b c d e f g h i j k l m n o p q r s t u v w x y z { | } ~

C Standard Library <ctype.h>