C++ the program must use a stack to convert the decimal number to the numeric format....

The C++ program is given below. The explaination is given as comment within the code itself.

#include <iostream>
#include <string>
#include <stack>
#include <math.h>

using namespace std;

int main() {
   string s; //store the number in string format
   double n=0; //store the number in decimal formal
   int pos=0; //used to convert string to number
   stack<int> st; //stack is used to store the whole number in reverse order
   cout<<"Enter a decimal number:";
   cin>>s;
   string::iterator it = s.begin();
   //Util we find a .(end of whole number) or the end of the number, push each digit ontostack and count the number of digits.
   while(*it!='.' && it!=s.end()){
       st.push(*it-48);
       it++;
       pos=pos+1;
      
   }
   //Convert the integral part of the number to n
   for(int i=0;i<pos;i++){
       n=n+(st.top()*pow(10,i));
       st.pop();
   }
   //consider the fractional part
   pos=-1;
   if(it!=s.end()){
       it++;//needed to shift iterator for .
   }
   //Convert the fractional part to n
   while(it!=s.end()){
       n=n+((*it-48)*pow(10,pos));
       pos=pos-1;
       it++;      
   }
   //Display the decimal number
   cout<<n;
}

The screenshot of the output is given below:

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