C Programming Examples Tutorial Index

C Number Programs

Converting hexadecimal to decimal is a fundamental concept in programming and computer science. This tutorial will guide you through writing an efficient C program that can convert any hexadecimal number to its equivalent decimal representation.

What is Hexadecimal to Decimal Conversion?

Hexadecimal to decimal conversion involves transforming numbers from the hexadecimal system (base 16), which uses the digits 0-9 and letters A-F, to the decimal system (base 10). This conversion is essential because hexadecimal numbers are often used in low-level and systems programming.

Algorithm for Hexadecimal to Decimal Conversion

  1. Initialize Variables: Declare variables for storing the hexadecimal number as a string and the decimal equivalent as an integer.
  2. Input Hexadecimal Number: Prompt the user to enter a hexadecimal number. Use scanf() to take the input.
  3. Conversion Process: Implement a loop that iterates through each character of the hexadecimal string, converting it to the corresponding decimal value and accumulating the result.
  4. Output Decimal Number: Display the converted decimal number using printf().

Code Example

A C Program for Hexadecimal to Decimal Conversion:

#include <stdio.h>
#include <string.h>
#include <math.h>

int main() {
    char hex[17];
    int decimal = 0, base = 1, length, i, value;

    // Take user input for the hexadecimal number
    printf("Enter a hexadecimal number: ");
    scanf("%16s", hex);

    length = strlen(hex);

    // Conversion process
    for(i = length - 1; i >= 0; i--) {
        if(hex[i] >= '0' && hex[i] <= '9') {
            value = hex[i] - '0';
        } else if(hex[i] >= 'A' && hex[i] <= 'F') {
            value = hex[i] - 'A' + 10;
        decimal += value * base;
        base = base * 16;

    // Display the decimal number
    printf("Decimal equivalent: %d\n", decimal);

    return 0;

Program Output:

For instance, inputting the hexadecimal number 1A3 will result in the program converting and displaying its decimal equivalent as 419.

Enter a hexadecimal number: 1A3
Decimal equivalent: 419


Creating a C program for converting hexadecimal to decimal numbers offers insight into how computers process and display numbers. This tutorial provides the knowledge to build a program that accurately executes this conversion, broadening your understanding of hexadecimal and decimal systems in computer programming.

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