Question

IMPLEMENT IN C++

Implement a symbol balance checker function for the Pascal programming language. Pascal allows for the following pairs: {}, (), [], begin end . All programs will begin with the word "begin" and end with the word "end". Your function should receive an ifstream object which is already open and will return true, all of the symbols match, or false, they do not. You do not have to worry about comments in the program but you do have to avoid other parts of the program's code such as assignment statements (x=y) and other expressions.

THIS IS HOW THE CODE WILL BE TESTED:

You should test with a test Pascal input program that you can validate is correct manually, and another that you can validate is incorrect. If it passes these tests, it should pass ours.

Every [ should have a matching ]

Every { should have a matching }

Every begin should have a matching end

Every ( should have a matching )

These can be nested in any order, and with any number of begins and ends.

So for instance, a valid test program would be:

begin

   { ignore this

      begin

          ignore this too

      end

   }

end

We are not going to be testing your code with Pascal code that has single bracket characters in strings like "}", so don't worry about that.

Answer 1

main.cpp:

#include<iostream>
#include<fstream>
#include<stack>
using namespace std;

// return true if file contains all currect matching otherwise return false
bool isCorrect(ifstream &ifs){
   stack<string> stk;
   string line;
   do {
       getline(ifs, line);
       if (line.find("begin") != string::npos){
           stk.push("begin");
       } else if (line.find("{") != string::npos){
           stk.push("{");
       } else if (line.find("(") != string::npos){
           stk.push("(");
       } else if (line.find("[") != string::npos){
           stk.push("[");
       } else if (line.find("end") != string::npos){
           if (stk.top() != "begin")
               return false;
           stk.pop();
       } else if (line.find("}") != string::npos){
           if (stk.top() != "{")
               return false;
           stk.pop();
       } else if (line.find(")") != string::npos){
           if (stk.top() != "(")
               return false;
           stk.pop();
       } else if (line.find("]") != string::npos){
           if (stk.top() != "]")
               return false;
           stk.pop();
       }

   } while (!ifs.eof());
  
   if (stk.empty()){
       return true;
   }
   return false;
}

int main(){
   ifstream ifs;
   ifs.open("input.txt");
  
   // check input.txt file have currect matching of not
   if (isCorrect(ifs)){
       cout<<"file contains all correct matching.";
   } else {
       cout<<"file not contains all correct matching.";
   }
  
   ifs.close();
}

input.txt:

begin

   { ignore this

      begin

          ignore this too

      end

   }

end

Output:

file contains all correct matching.