C Exercises: Convert a decimal number to hexadecimal

Last update on March 18 2025 13:34:27 (UTC/GMT +8 hours)

55. Decimal to Hexadecimal Conversion

Write a C program to convert a decimal number to hexadecimal.

This C program converts a decimal number into its hexadecimal equivalent. It prompts the user to input a decimal number, then iteratively divides it by 16, storing the remainders as hexadecimal digits in an array. Finally, it prints the hexadecimal number by traversing the array in reverse order and printing each digit.

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h>
int main() {
    // Declare variables
    long int decn, q, m;
    int tmp;
    // Print output header
    printf("\n\nConvert Decimal to Hexadecimal:\n ");
    printf("-------------------------\n");
    // Get decimal input
    printf("Input any Decimal number: ");
    scanf("%ld", &decn);
    // Convert decimal to hex
    // Use an array to store hex digits
    char hexDigits[20];  // Adjust the size as needed
    int index = 0;  // Index to store hex digits in the array
    while (decn > 0) {
        // Get remainder
        tmp = decn % 16;
        // Convert to hex digit
        if (tmp < 10) {
            hexDigits[index] = tmp + '0';
        } else {
            hexDigits[index] = tmp + 'A' - 10;
        }
        index++;
        decn = decn / 16;
    }
    // Print hex number in reverse order
    printf("\nThe equivalent Hexadecimal Number : ");
    for (int i = index - 1; i >= 0; i--) {
        printf("%c", hexDigits[i]);
    }
    printf("\n\n");
    return 0;
}

Output:

Convert Decimal to Hexadecimal:                                                                               
 -------------------------                                                                                    
Input  any Decimal number: 79                                                                                 
                                                                                                              
The equivalent Hexadecimal Number : 4F

Explanation:

Here's a brief explanation.

Header and Declaration:

Includes the necessary header file (stdio.h).
Declare variables 'decn' (decimal input), 'q' (temporary variable), 'm' (temporary variable), and 'tmp' (temporary variable for remainder).
Declares an array 'hexDigits' to store the hexadecimal digits.

User Input:

Asks the user to input a decimal number.
Reads the input and stores it in the variable 'decn'.

Conversion Loop:

Enters a while loop that continues until the decimal number ('decn') becomes zero.
Inside the loop, calculate the remainder when dividing 'decn' by 16 ('tmp').
Converts the remainder to a hexadecimal digit and stores it in the 'hexDigits' array.
Update the 'decn' by dividing it by 16.

Print Hexadecimal Result:

Prints the header for hexadecimal output.
Prints the equivalent hexadecimal number by iterating through the 'hexDigits' array in reverse order.

Return Statement:

Returns 0 to indicate successful execution.

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to convert a decimal number to hexadecimal using the division-remainder method.
Write a C program to convert a decimal number to hexadecimal without using arrays by using recursion.
Write a C program to convert a decimal number to hexadecimal and display the result in uppercase letters.
Write a C program to convert a decimal number to hexadecimal and verify the conversion by converting back to decimal.

C Programming Code Editor:

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