ispunct() function checks whether a character is punctuation character or not. A character is a punctuation character, If it is a graphical character but not an alphanumeric character.
For Example
% & ‘ $ + – * ? etc.
Function prototype of ispunct
int ispunct(int c);
Function ispunct() takes a character as input in form of an integer. When we pass a value of type char to ispunct() function, corresponding ASCII value of that character is passed.
Return value of ispunct
If passed character is a punctuation character, then ispunct function returns non-zero(true) integer otherwise 0(false).
C program using ispunct function
The following program is to check whether a character is punctuation character or not.

#include <stdio.h>
#include <ctype.h>
#include <conio.h>
int main(){
char string[] = "A1,/?";
int index = 0;
while(string[index] != '\0'){
if(ispunct(string[index])){
printf("'%c' is a punctuation character\n", string[index]);
} else {
printf("'%c' is not a punctuation character\n", string[index]);
}
index++;
}
getch();
return 0;
}
Output
'A' is not a punctuation character '1' is not a punctuation character ',' is a punctuation character '/' is a punctuation character '?' is a punctuation character