# `isdigit()`

The **`isdigit()` function** falls under the header file ctype.h.

Header file :
```c
#include<ctype.h>
```
This function accepts a character and classifies the character as a digit. It returns a value other than `0` to indicate success.
The `isdigit()` function checks if the character is a #key# numeric character: in between 0 to 9 #key#.
Although `isdigit()` accepts an integer as an argument, when a character is passed to the function it internally converts the character to an ASCII value.

**Syntax**:
```
int isdigit(int a);
```
Here, `a` is the character to be checked.
>Note:
If the character passed as argument in `isdigit()` function is a digit, a non zero value is returned. If the character passed as argument in the `isdigit()` function is not a digit, 0 is returned.

# Code

Below is a simple program that checks to see if it is a digit:

#include <stdio.h> 
#include<ctype.h>

int main() 
{  char ch='8';
   
   if(isdigit(ch))
   {
     printf("condition is true");
     
   }
   else
   {
   	printf("condition is false");
   }
}
   

# `ispunct()`

The **`ispunct()`** function falls under the `ctype.h` header file.

Header file :
```c
#include<ctype.h>
```
The `ispunct()` function is used to determine if a character is a punctuation mark.

**Syntax:**
```c
int ispunct(int argument);
```
If the character passed to the `ispunct()` function is punctuation, then a non-zero integer is returned. If not, it returns `0`.

![](/api/edpresso/shot/6474829174145024/image/5958445969178624)

# Code

The program below checks for punctuation in a sentence:

#include <stdio.h>
#include <ctype.h>
int main()
{
   
    char str[] = "Alas!, You have won the prize. ";
  
    int i = 0, value=0;
    while (str[i]) {          //iterating through the string
        if (ispunct(str[i]))  //checking the condition
            value++;
        i++;
    }
    printf("The sentence has  %d punctuation"
           " characters.\n", value);
    return 0;
}

![](/api/edpresso/shot/6474829174145024/image/4545898829316096)

What are isdigit() and ispunct() functions in C?

isdigit()

Code

ispunct()

Code

`isdigit()`

`ispunct()`