Hexadecimal Number To Decimal Number Using C++ ( With Condition Check)

 => Program :

#include<iostream>

#include<math.h>

using namespace std;

string low2up(string passStr){

string changeStr=passStr;

for(int i=0;i<changeStr.size();i++){

     if(passStr[i]>=97 && passStr[i]<=122)

      {

changeStr[i]=changeStr[i]-32;

      }

}

return changeStr;

}

bool validHexVal(string checkSr){

bool checkValid;

int countNum=0;

for(int i=0;i<checkSr.size();i++){

     if(checkSr[i]>=65 && checkSr[i]<=70)

      {

countNum++;

      }

      if(checkSr[i]>=48 && checkSr[i]<=57){

        countNum++;

      }

}

if(checkSr.size()==countNum){

    return true;

}else{

    return false;

}

}

int main(){

int decNum=0,val;

string hexNum,upperHexNum;

cout<<"Enter the hex decimal number "<<endl;

cin>>hexNum;

upperHexNum=low2up(hexNum);

int n=upperHexNum.size();

if(validHexVal(upperHexNum)){

 for(int i=n-1;i>=0;i--){

    if(upperHexNum[i]>=65 && upperHexNum[i]<=70)

      {

val=char(upperHexNum[i])-55;

      }else{

        val=char(upperHexNum[i])-48;

      }

      decNum=decNum+val*pow(16,n-(i+1));

 }

cout<<"Decimal Value : "<<decNum<<endl;

}else{

   cout<<"Not Valid Hexadecimal Value";

}

}

=> Output: