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Need help getting started on my Infix/prefix/postfix conversion program

tit0n (21)
Need some hints/tips on how this might look. I am a beginner to C++ so any help or details that look wrong please help!

Also I am unsure why I keep getting an error for

bool Expression::isOperator(){

prototype for 'bool Expression::isOperator()' does not match any in class 'Expression'|

Thank you.

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  #include <iostream>
#include <fstream>
#include <stack>
#include <string>

using namespace std;

class Expression{
    public:
        Expression (string input, int direction);    //edited this in
        string inToPost();
        string inToPre();
        string postToIn();
        string preToIn();
        string convertThis;  // Expression that we want converted
        double evaluate();
        bool isOperator();
        Expression();
        char symbol;
    

        int direction;
    private:
        string infix;
        string postfix;
        string prefix;


};


Expression::Expression(){    // Constructor
    switch (direction){
        case 1: infix = convertThis;
        case 2: postfix = convertThis;
        case 3: prefix = convertThis;

    }
}

                                 //Function checks to see if convertThis contains valid symbol
bool Expression::isOperator(){            // error is occurring here.

	    if((symbol == '*')||(symbol == '+')||(symbol == '-')||(symbol == '/'))

                    return true;

	              else

                    return false;
	}
        string Expression::inToPost(){

                                                //converting with stack "S"
    stack<char> S;
	string postfix = "";                        // Initialize postfix as empty string.
	for(int i = 0;i< convertThis.length();i++){

        // Checking characters from left
        // If character is delimitter.. skip

        if(convertThis[i] == ' ' || convertThis[i] == ',') continue;

        // If character is operator, pop two elements from stack, perform operation and push the result back.
		else if(isOperator(convertThis[i])){
         S.push(convertThis[i]);
        }
    }
}
        string Expression::inToPre(){




}
        string Expression::postToIn(){



}
        string Expression::preToIn(){



}





        double Expression::evaluate(){




}







int main(){

string convertThis;



int choice;


cout << "|-----Here is my conversion menu-----|" << endl;
cout << "|----What are you converting to?-----|" << endl << endl;
cout << "1- Infix to postfix" << endl;
cout << "2- Infix to prefix" << endl;
cout << "3- postfix to infix?" << endl;
cout << "4- prefix to infix?" << endl;
cin >> choice;
cin.ignore();

cout << "Now enter the expression you want to convert ";
getline(cin,convertThis);


bool isOperator();
string inToPost();
string inToPre();


}
Last edited on
cire (8284)
bool Expression::isOperator(){

prototype for 'bool Expression::isOperator()' does not match any in class 'Expression'|

Are you sure about the error occurring there? That looks fine to me. On the other hand on line 64 you are trying to call that same method which doesn't have any parameters with an argument (which it is incapable of taking.)

Also:
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bool isOperator();
string inToPost();
string inToPre();
These are function declarations. They don't do anything.

In your constructor you're using the value stored in the variable direction which is uninitialized and results in undefined behavior.
tit0n (21)
Yes it is line 64 I am sorry. Not sure how I can fix this issue just by reading what you said.

I added Expression (string input, int direction); to the public class.
Last edited on
cire (8284)
Yes it is line 64 I am sorry. Not sure how I can fix this issue just by reading what you said.

They way you're using symbol it should not be a member of the class.

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class Expression{
    public:
        Expression (string input, int direction);    //edited this in
        string inToPost();
        string inToPre();
        string postToIn();
        string preToIn();
        string convertThis;  // Expression that we want converted
        double evaluate();
        bool isOperator( char symbol );
        Expression();
        char symbol;
    

        int direction;
    private:
        string infix;
        string postfix;
        string prefix;
};


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bool Expression::isOperator( char symbol ){
    return symbol == '*' || symbol == '+' || symbol == '-' || symbol == '/';
}

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