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C++ Exercises: Convert a hexadecimal number to decimal number

C++ For Loop: Exercise-79 with Solution

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

Pictorial Presentation:

C++ Exercises: Convert a hexadecimal number to decimal number

Sample Solution:-

C++ Code :

#include<iostream>
#include<stdlib.h>
#include<math.h>
using namespace std; 
 
unsigned long Hex_To_Dec(char hex[]) 
{
  char *hexstring;
  int length = 0;
  const int hexbase = 16;     
  unsigned long dnum = 0;
  int i;
  for (hexstring = hex; *hexstring != '\0'; hexstring++) 
  {
      length++;
    }
  hexstring = hex;
  for (i = 0; *hexstring != '\0' && i < length; i++, hexstring++) 
  {
      if (*hexstring >= 48 && *hexstring <= 57) 
	  {  
          dnum += (((int)(*hexstring)) - 48) * pow(hexbase, length - i - 1);
        }
      else if ((*hexstring >= 65 && *hexstring <= 70))  
	  {  
          dnum += (((int)(*hexstring)) - 55) * pow(hexbase, length - i - 1);
        }
      else if (*hexstring >= 97 && *hexstring <= 102) 
	  {  
          dnum += (((int)(*hexstring)) - 87) * pow(hexbase, length - i - 1);
        }
      else {
          cout<<" The given hexadecimal number is invalid. \n";
        }
    }
  return dnum;
}
int  main() 
{
  unsigned long dnum;
  char hex[9];
	cout << "\n\n Convert any hexadecimal number to decimal number:\n";
	cout << "------------------------------------------------------\n";
	cout << " Input any 32-bit Hexadecimal Number: ";  
    cin>>hex;
 dnum = Hex_To_Dec(hex);
  cout<<" The value in decimal number is: "<<dnum<<"\n";
}

Sample Output:

 Convert any hexadecimal number to decimal number:                     
------------------------------------------------------                 
 Input any 32-bit Hexadecimal Number: 25                               
 The value in decimal number is: 37

Flowchart:

Flowchart: Convert a hexadecimal number to decimal number

C++ Code Editor:

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Previous: Write a program in C++ to convert a octal number to a hexadecimal number.
Next: Write a program in C++ to convert hexadecimal number to binary number.

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C++ Programming: Tips of the Day

What is a smart pointer and when should I use one?

This answer is rather old, and so describes what was 'good' at the time, which was smart pointers provided by the Boost library. Since C++11, the standard library has provided sufficient smart pointers types, and so you should favour the use of std::unique_ptr, std::shared_ptr and std::weak_ptr.

There was also std::auto_ptr. It was very much like a scoped pointer, except that it also had the "special" dangerous ability to be copied - which also unexpectedly transfers ownership.

It was deprecated in C++11 and removed in C++17, so you shouldn't use it.

std::auto_ptr<MyObject> p1 (new MyObject());
std::auto_ptr<MyObject> p2 = p1; // Copy and transfer ownership. 
                                 // p1 gets set to empty!
p2->DoSomething(); // Works.
p1->DoSomething(); // Oh oh. Hopefully raises some NULL pointer exception.

Ref : https://bit.ly/3mc9GHE