C Program For Char to Int Conversion

Last Updated : 23 Jul, 2025

Write a C program to convert the given numeric character to integer.

Example:

Input: '3'
Output: 3
Explanation: The character '3' is converted to the integer 3.

Input: '9'
Output: 9
Explanation: The character '9' is converted to the integer 9.

Different Methods to Convert the char to int in C

There are 3 main methods to convert the char to int in C language as follows:

Table of Content

Let's discuss each of these methods in detail.

1. Using ASCII Values

Each character in C has an ASCII value, a unique numerical representation. For numeric characters like '0', '1', etc., the ASCII value starts from 48 for '0' and increases sequentially. To convert a char to its integer equivalent, subtract the ASCII value of '0' from the character.

C Program to Convert char to int Using ASCII Values

C 
// C program to convert the given char to int using
// ASCII values
#include <stdio.h>

int main() {
  
    // Define a numeric character variable
    char ch = '7';

    // Convert the character to integer by subtracting
  	// ASCII value of '0'
    int N = ch - '0';

    // Print the result
    printf("The integer value of character '%c' is %d\n", ch, N);

    return 0;
}

Output
The integer value of character '7' is 7

Time Complexity: O(1)
Space Complexity: O(1)

2. Using sscanf() Function

The sscanf() function can be used to read formatted input from a string. It can convert a character to an integer by treating the character as a string and reading it using the format specifier for an integer (%d).

C Program to Convert char to int Using sscanf() Function

C 
// C program to demonstrate conversion of
// char to int using sscanf()
#include <stdio.h>

int main() {
  
    // Define a character variable
    char ch = '8';

    // Declare an integer variable to store the converted value
    int N;

    // Use sscanf to convert the character to an integer
    sscanf(&ch, "%d", &N);

    printf("The integer value of character '%c' is %d\n", ch, N);

    return 0;
}

Output
103

Time Complexity: O(1)
Space Complexity: O(1)

3. Using atoi() Function

The atoi() function from the C Standard Library <stdlib.h> can convert a string of digits into an integer. Although atoi() is designed for strings, it can be used with single-character strings.

C Program to Convert char to int Using atoi()

C 
// C program to demonstrate conversion of char to int
// using atoi()
#include <stdio.h>
#include <stdlib.h>

int main() {
  
    // Define a character variable
    char ch = '5';

    // Convert the character to a string and then use
    // atoi() to convert it to an integer
    int N = atoi(&ch);

    // Print the result
    printf("The integer value of character '%c' is %d\n", ch, N);

    return 0;
}

Output
The integer value of character '5' is 5

Time Complexity: O(1)
Space Complexity: O(1)

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