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Problems with converting string to an Integer in a calculator program

boaschri (7)
Hey im having problems with my program and i am not sure whats wrong.i will underline what i think is not working I do know that error messages pop up telling me that i can not convert string to const char can you help me out, here is my code:
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#include <iostream>
#include <stack>
#include<string>
using namespace std;
 

int OrderOfOpsCheck(char);
 

int main()
{
stack<int> aStack;
stack<char> bStack;
int temp1, temp2, temp ,optype, startposn ,tempnum ;
 
string express, eString,   mchac ,   tempstr ; 
cout<<"please enter an expression"<<endl;
cin>>express;  
 
optype =0 ;
startposn= -1 ;
for(int j = 0; j < express.length(); j++)
{
      if(isdigit(express[j]))
      {   
           if  ( startposn== -1 )   
           {    startposn = j ; 
           }
           optype=1 ; 
      }
      else if ((express[j] == '+') || (express[j] == '-') || (express[j] == '*') || (express[j] == '/'))
      {     
            if  ( optype==1 )      
            {        // when the last  entry was numeric then put number on stack 
                       tempstr=  express.substr(startposn , j-startposn-1)  ;      
                       tempnum = atoi(tempstr.c_str());;    
                       //aStack.push(  tempstr-'0');                
                      aStack.push(tempnum);                
                       startposn = -1 ; 
            }
              optype =0 ; 
              if(bStack.empty() == false)    
               { 
                   // if something exists already on operations stack, check if need to resolve order of operations 
                   while(OrderOfOpsCheck(bStack.top()) >= OrderOfOpsCheck(express[j]))   
                   {
                          if(bStack.top() == '+' ||bStack.top() == '-' || bStack.top() =='*' ||bStack.top() == '/')      
                          {  
                              // pop two entries off stack and process them then put result back on stack                               
                              temp2 = aStack.top();
                              aStack.pop();
                              temp1 = aStack.top();
                              aStack.pop();
                              switch(bStack.top())
                              {
                                  case '+': temp = temp1 + temp2;
                                    break;
                                  case '-': temp = temp1 - temp2;
                                    break;
                                  case '*': temp = temp1 * temp2;
                                  break;
                                    case '/': temp = temp1 / temp2;
                                  break;
                                  default: cout << "There was an invalid operator, press any key to terminate.";
                              } 
                          aStack.push(temp);
                       } 
                      bStack.pop(); 
                      if(bStack.empty() == true)
                      {
                          break;
                      }
                  }
              }     
              bStack.push(express[j]); // places items on top of stack 
      } 
      else if(express[j] == '(')
      {  
            if  ( optype==1 )      
            {        // when the last  entry was numeric then put number on stack 
                       tempstr=  express.substr(startposn , j-startposn-1)  ;      
                     tempnum = atoi(tempstr.c_str());
  
 //                       aStack.push(  tempstr-'0');                
                      aStack.push(tempnum);                
                       startposn = -1 ; 
            }
              optype =0 ; 
              bStack.push (express[j]);
      }
     else if(express[j] == ')')
     { 
         
            if  ( optype==1 )      
            {        // when the last  entry was numeric then put number on stack 
                       tempstr=  express.substr(startposn , j-startposn-1)  ;      
                     tempnum = atoi(tempstr.c_str());  
 //                       aStack.push(  tempstr-'0');                
                      aStack.push(tempnum);                
                       startposn = -1 ; 
            }
              optype =0 ; 
              if(bStack.empty() == false)
              { 
                  // process entries on stack until we reach open bracket
                  while(bStack.top() != '(')
                  {
                       if(bStack.top() == '+' ||bStack.top() == '-' || bStack.top() =='*' ||bStack.top() == '/')      
                       { 
                          temp2 = aStack.top();
                          aStack.pop();
                          temp1 = aStack.top();
                          aStack.pop();
                          switch(bStack.top())
                          {
                              case '+': temp = temp1 + temp2;
                              break;
                              case '-': temp = temp1 - temp2;
                              break;
                              case '*': temp = temp1 * temp2;
                              break;
                              case '/': temp = temp1 / temp2;
                              break;
                              default: cout << "There was an invalid operator, press any key to terminate.";
                          }
                          aStack.push(temp);
                       }
                       bStack.pop();
                       if(bStack.empty() == true)
                       {
                          break;
                       }                              //POP the content in Stack until “(“ is reached,
                  }
              }
              bStack.pop();                    //POP it ; break;
     } 
if  ( optype==1 )   // if at the end of string check if last item processed was number if so pop on stack 
	{
		tempstr=express.substr(startposn , j-startposn-1);   
        tempnum = atoi(tempstr.c_str());
		aStack.push(tempnum-'0');                       // place final number on top of stack
	}
}

      
while(!(bStack.empty()))
    {
 

        if(bStack.top() == '+' ||bStack.top() == '-' || bStack.top() =='*' ||bStack.top() == '/' )
        {
            temp2 = aStack.top();
            aStack.pop();
            temp1 = aStack.top();
            aStack.pop();
            switch(bStack.top())
            {
                case '*': temp = temp1 * temp2;
                    break;
                case '/': temp = temp1 / temp2;
                    break;
                case '+': temp = temp1 + temp2;
                    break;
                case '-': temp = temp1 - temp2;
                    break;
                default: cout << "There was an invalid operator, press any key to terminate.";
            }
 
            aStack.push(temp);
        }
        bStack.pop();
    }  
    
cout << endl << "The answer is: " << temp << endl;
cin.ignore();
cin.clear();
cin.get();
return 0;
}
 
int OrderOfOpsCheck(char operation)
{
    int check;
    switch(operation)
    {
        case '/': 
        case '*': check= 2;
        break;
        case '+':
        case '-': check= 1;
        break;
        case '(':
        case ')': check= 0;
        break;
    }
    return (check);
}
Last edited on
kbw (9488)
tempnum = atoi(tempstr.c_str());
boaschri (7)
Thanks that helped solve one of the problems. It now builds correctly but now i get a error when it executes i enter in the expression and press enter and i get this error:

Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.
kbw (9488)
These don't do what you might think they do:
else if (express[j] == '+' || '-' || '*' || '/')

if ( optype=1 )

if(bStack.top() == '+' || '-' || '*' || '/' )

All expressions return true.
Last edited on
boaschri (7)
Thanks that solved that problem now its coming out with the wrong answer:)
such as 1+1 is -47
and 1+2 is -46 so their is probably some kind of reason that when i add to the next number(1+3=-45) so the math is wrong right?
kbw (9488)
Have you tried debugging your program?
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