C++

Forum

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

Feb 23, 2017 at 1:25am
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.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
 
  #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();


}
Edit & run on cpp.sh
Last edited on Feb 23, 2017 at 2:22am
Feb 23, 2017 at 2:04am
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:
1
2
3
 
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.
Feb 23, 2017 at 2:15am
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 Feb 23, 2017 at 2:23am
Feb 23, 2017 at 3:20am
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.

8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
 
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;
};


42
43
44
 
bool Expression::isOperator( char symbol ){
    return symbol == '*' || symbol == '+' || symbol == '-' || symbol == '/';
}

Topic archived. No new replies allowed.