C++ program for hexadecimal to decimal

C++Server Side ProgrammingProgramming

Given with a hexadecimal number as an input, the task is to convert the given hexadecimal number into a decimal number.

Hexadecimal number in computers is represented with base 16 and decimal number is represented with base 10 and represented with values 0 - 9 whereas hexadecimal number have digits starting from 0 – 15 in which 10 is represented as A, 11 as B, 12 as C, 13 as D, 14 as E and 15 as F.

To convert a hexadecimal number into a decimal number follow these steps −

  • We will extract digits starting from right to left through a remainder and then multiply it with the power starting from 0 and will be increased by 1 till the (number of digits) – 1
  • Since we need to do conversions from hexdecimal to binary the base of power will be 16 as octal have base 16.
  • Multiply the digits of given inputs with base and power and store the results
  • Add all the multiplied values to obtain the final result which will be a decimal number.

Given below is the pictorial representation of converting a hexadecimal number into a decimal number.

Example

Input-: ACD
   A(10) will be converted to a decimal number by -: 10 X 16^2 = 2560
   C(12) will be converted to a decimal number by -: 12 X 16^1 = 192
   D(13) will be converted to a decimal number by -: 13 X 16^0 = 13
Output-: total = 13 + 192 + 2560 = 2765

Algorithm

Start
Step 1-> declare function to convert hexadecimal to decimal
   int convert(char num[])
      Set int len = strlen(num)
      Set int base = 1
      Set int temp = 0
      Loop For int i=len-1 and i>=0 and i—
         IF (num[i]>='0' && num[i]<='9')
            Set temp += (num[i] - 48)*base
            Set base = base * 16
         End
         Else If (num[i]>='A' && num[i]<='F')
            Set temp += (num[i] - 55)*base
            Set base = base*16
         End
         return temp
step 2-> In main()
   declare char num[] = "3F456A"
   Call convert(num)
Stop

Example

 Live Demo

#include<iostream>
#include<string.h>
using namespace std;
//convert hexadecimal to decimal
int convert(char num[]) {
   int len = strlen(num);
   int base = 1;
   int temp = 0;
   for (int i=len-1; i>=0; i--) {
      if (num[i]>='0' && num[i]<='9') {
         temp += (num[i] - 48)*base;
         base = base * 16;
      }
      else if (num[i]>='A' && num[i]<='F') {
         temp += (num[i] - 55)*base;
         base = base*16;
      }
   }
   return temp;
}
int main() {
   char num[] = "3F456A";
   cout<<num<<" after converting to deciaml becomes : "<<convert(num)<<endl;
   return 0;
}

Output

IF WE RUN THE ABOVE CODE IT WILL GENERATE FOLLOWING OUTPUT

3F456A after converting to deciaml becomes : 4146538
raja
Published on 18-Oct-2019 08:44:50
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