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Dequeue iterator not found

Discussion in 'C++' started by imueed, Nov 13, 2015.

  1. imueed

    imueed New Member

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    I'm making a program that turns infix to postfix.
    Please identify the error
    Code:
    #include <iostream>
    #include <string>
    #include <stack>
    using namespace std;
    
    double solve_expression(string infix);
    string convert_to_postfix(string infix);
    double evaluate_postfix(string postfix);
    
    void main()
    {
    	do{
    		cout<<"Press 1 to convert infix to postfix"<<endl;
    		cout<<"Press 2 to evaluate postfix expression"<<endl;
    		cout<<"Press E/e to EXIT"<<endl;
    		char option='0';
    		cin>>option;
    		system("CLS");
    
    		switch(option)
    		{
    		case '1':
    			{
    				cout<<"Question 1"<<endl;
    			
    				stack <char> output;
    				string infix="(1+2–3)*4–(5+6)";
    				string postfix;
    
    				postfix= convert_to_postfix(infix);
    				cout<<postfix;
    				
    				
    
    
    				break;
    			}
    
    		case '2':
    			{
    				cout<<"Question 2"<<endl;
    				break;
    			}
    
    		case 'E':
    		case 'e':
    			{
    				exit (-1);
    			}
    
    		default:
    			{
    				cout<<"Invalid input"<<endl;
    			}
    
    
    	}
    
    }
    		while (-1);
    }
    
    string convert_to_postfix(string infix)
    {
    	string output="";
    	stack <char> op;
    	for(int i=0;i<infix.length();i++)
    	{
    		if(infix[i]=='0'||infix[i]=='1'||infix[i]=='2'||infix[i]=='3'||infix[i]=='4'||infix[i]=='5'||infix[i]=='6'||infix[i]=='7'||infix[i]=='8'||infix[i]=='9')
    		{
    			char c=infix[i];
    			output+=c;
    		}
    
    		if(infix[i]=='(')
    		{
    			op.push(infix[i]);
    		}
    
    		if(infix[i]=='/'||infix[i]=='*'||infix[i]=='+'||infix[i]=='-')
    		{
    			while(op.top()>infix[i]||op.top()==infix[i])
    			{
    				char c=op.top();
    				op.pop();
    				output+=c;
    			}
    
    			op.push(infix[i]);
    		}
    
    		if(infix[i]==')')
    		{
    			while(infix[i]!='(')
    			{
    				char c=op.top();
    				op.pop();
    				output+=c;
    			}
    		}
    
    				
    		
    }
    	while(!op.empty())
    		{
    				char c=op.top();
    				op.pop();
    				output+=c;
    		}
    
    	return output;
    }
     
  2. xpi0t0s

    xpi0t0s Mentor

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    There's an error on line 10.

    Does it compile OK? If not, what errors do you get?
    What output do you get when you run the program?

    Try adding some debug statements; that should help you find the error. If the problem is that you get a crash, make sure you use fflush(stdout); so that the screen output accurately reflects the latest message printed by the code.
     

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