c++ Delimiter Matching - c++

Question

This program basically just checks that a statement (mathematical) is properly constructed considering the brackets, parenthesis, and curly-braces. It uses a stack to compare the most recently read delimiter to see if the ending type of that delimiter exists, otherwise it says it is not constructed properly. I'm stuck, as it always returns that the statement is incorrect. This is what I have so far:
#include <iostream>
#include <stack>
using namespace std;
bool delimiterMatching(char* file);
void main(){
char fileName[50];
cout << "Enter a statement (Ex. s=t[5]+u/(v*(w+y)); : ";
cin >> fileName;
cout << endl;
if(delimiterMatching(fileName))
cout << endl << "Your statement was constructed successfully." << endl;
else cout << endl << "Your statement is incorrectly constructed." << endl;
}
bool delimiterMatching(char* file){
stack<char> var;
int counter = 0;
char ch, temp, popd;
do{
ch = file[counter];
if(ch == '(' || ch == '[' || ch == '{')
var.push(ch);
else if(ch == '/'){
temp = file[counter+1];
if(temp == '*')
var.push(ch);
else{
ch = temp;
continue;
}
}
else if(ch == ')' || ch == ']' || ch == '}'){
popd = var.top();
var.pop();
if(ch != popd)
return false;
}
else if(ch == '*'){
temp = file[counter+1];
popd = var.top();
var.pop();
if(temp == '/' && popd != '/')
return false;
else{
ch = temp;
var.push(popd);
continue;
}
}
counter++;
}while(ch != '\n');
if(var.empty())
return true;
else return false;
}
I've already tried googling for some hints, but got nothing too helpful. I debugged it, and if I use "s=t[5]+u/(v*(w+y));", when it reads the second bracket after the 5, it obviously isn't the same char. So how do I compare the opening symbol with the ending symbol?
I appreciate any help. I'll edit this/comment it if I figure it out myself. Thanks for your time!
I got it working this is the final code:
#include <iostream>
#include <stack>
using namespace std;
bool delimiterMatching(char* file);
void main(){
char fileName[50];
cout << "Enter a statement (Ex. s=t[5]+u/(v*(w+y)); : ";
cin >> fileName;
cout << endl;
if(delimiterMatching(fileName))
cout << endl << "Your statement was constructed successfully." << endl;
else cout << endl << "Your statement is incorrectly constructed." << endl;
}
bool delimiterMatching(char* file){
stack<char> var;
int counter = 0;
char ch, temp, popd;
do{
ch = file[counter];
if(ch == ';')
break;
if(ch == '(' || ch == '[' || ch == '{')
var.push(ch);
else if(ch == '/'){
temp = file[counter+1];
if(temp == '*')
var.push(ch);
else{
counter++;
continue;
}
}
else if(ch == ')' || ch == ']' || ch == '}'){
popd = var.top();
var.pop();
if((ch==')' && popd!='(') || (ch==']' && popd!='[') || (ch=='}' && popd!='{'))
return false;
}
else if(ch == '*'){
temp = file[counter+1];
popd = var.top();
var.pop();
if(temp == '/' && popd != '/')
return false;
else{
counter++;
var.push(popd);
continue;
}
}
counter++;
}while(ch != '\n');
if(var.empty())
return true;
else return false;
}

Answer 1

Your checking if the closing bracket (eg. ')', ']' or '}') matches the value popped off the stack. They are never going to be equal because you are only pushing the left sides of the brackets ('(', '[' or '{'), while comparing it with the right side of the brackets.
It should look something like this:
else if(ch == ')' || ch == ']' || ch == '}'){
popd = var.top();
var.pop();
if((ch==')' && popd!='(') || (ch==']' && popd!='[') || (ch=='}' && popd!='{'))
return false;
}