C Program For Hexadecimal to Decimal Conversion

// C program to demonstrate hexadecimal to decimal
// conversion using format specifier

#include <stdio.h>

int main()
{

    int n;
    // taking input from user
    scanf("%x", &n);
  
    // printing the decimal number
    printf("%d", n);
    return 0;
}

// C program to demonstrate hexadecimal to decimal
// conversion using switch case
#include <math.h>
#include <stdio.h>
#include <string.h>
int main()
{

    char hexdecnumber[32] = "2D";
    int decimalnumber, i;
  
    // used to store the power index
    int cnt;
  
    // used to store the digit
    int digit;

    cnt = 0;
    decimalnumber = 0;
  
    // iterating the loop using length of hexadecnumber
    for (i = (strlen(hexdecnumber) - 1); i >= 0; i--) {
      
        // using switch case finding the equivalent decimal
        // digit for each hexa digit
        switch (hexdecnumber[i]) {
        case 'A':
            digit = 10;
            break;
        case 'B':
            digit = 11;
            break;
        case 'C':
            digit = 12;
            break;
        case 'D':
            digit = 13;
            break;
        case 'E':
            digit = 14;
            break;
        case 'F':
            digit = 15;
            break;
        default:
            digit = hexdecnumber[i] - 0x30;
        }
      
        // obtaining the decimal number
        decimalnumber = decimalnumber + (digit)*pow((double)16, (double)cnt);
        cnt++;
    }
    // printing the decimal number
    printf("Decimal number is: %d", decimalnumber);
    return 0;
}

// C program to demonstrate hexadecimal to decimal
// conversion using an array
#include <math.h>
#include <stdio.h>
#include <string.h>

int main()
{
    int decimalNumber = 0;
  
    // Storing hexa number digits in one array
    char hexDigits[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
                           '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
    char hexadecimalnumber[30] = "2D";
    int i, j, power = 0, digit;

    // Converting hexadecimal number to equivalent decimal
    // number
    for (i = strlen(hexadecimalnumber) - 1; i >= 0; i--) {

        // search if given input character is present in the
        // array or not. if it present in the array then
        // find the equivalent decimal number for each hexa
        // digit
        for (j = 0; j < 16; j++) {
            if (hexadecimalnumber[i] == hexDigits[j]) {
                decimalNumber += j * pow(16, power);
            }
        }
        power++;
    }
    // printing the result
    printf("Decimal Number : %d", decimalNumber);

    return 0;
}

// C program to demonstrate hexadecimal to decimal
// conversion using while loop
#include <math.h>
#include <stdio.h>
#include <string.h>
int main()
{
    char hexdecnumber[17] = "2D";
    int decimalnumber, place;
    int i = 0, val, len;
    decimalnumber = 0;

    // finding the length of hexadecnumber
    len = strlen(hexdecnumber);
    len--;

    // while loop executes the statements until the
    // condition is false
    while (hexdecnumber[i] != '\0') {

        // finding the equivalent decimal digit for each
        // hexa decimal digit
        if (hexdecnumber[i] >= '0'
            && hexdecnumber[i] <= '9') {
            val = hexdecnumber[i] - 48;
        }
        else if (hexdecnumber[i] >= 'a'
                 && hexdecnumber[i] <= 'f') {
            val = hexdecnumber[i] - 97 + 10;
        }
        else if (hexdecnumber[i] >= 'A'
                 && hexdecnumber[i] <= 'F') {
            val = hexdecnumber[i] - 65 + 10;
        }
        // final decimal number
        decimalnumber += val * pow(16, len);
        len--;
        i++;
    }
    // printing the result
    printf("Hexadecimal number = %s\n", hexdecnumber);
    printf("Decimal number = %d", decimalnumber);
    return 0;
}

// C program to demonstrate hexadecimal to decimal
// conversion using for loop
#include <math.h>
#include <stdio.h>
#include <string.h>
int main() {

    char hexdecnumber[17] = "2D";
    long long decimalnumber, place;
    int i = 0, val, len;

    decimalnumber = 0;
    place = 1;

    // Find the length of total number of hex digit
    // finding the length of hexa decimal number
    len = strlen(hexdecnumber);
    len--;

    // for loop iterates the hexa decimal number digits
    for (i = 0; hexdecnumber[i] != '\0'; i++) {

        // finding the equivalent decimal digit for each
        // hexa decimal digit
        if (hexdecnumber[i] >= '0'
            && hexdecnumber[i] <= '9') {
            val = hexdecnumber[i] - 48;
        }
        else if (hexdecnumber[i] >= 'a'
                 && hexdecnumber[i] <= 'f') {
            val = hexdecnumber[i] - 97 + 10;
        }
        else if (hexdecnumber[i] >= 'A'
                 && hexdecnumber[i] <= 'F') {
            val = hexdecnumber[i] - 65 + 10;
        }

        decimalnumber += val * pow(16, len);
        len--;
    }
    // printing the result
    printf("Hexadecimal number = %s\n", hexdecnumber);
    printf("Decimal number = %lld", decimalnumber);
    return 0;
}