"inString not declared in this scope" [closed] - c++

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Working on an implementation of the Shunting Yard algorithm and I keep getting this error (In function 'void InputString()': 'inString was not declared in this scope') when trying to compile (what little) code I have - not entirely sure what could be causing it.
#include <iostream>
#include <string>
#include <stack>
#ifndef SHUNTINGYARD_H
#define SHUNTINGYARD_H
class ShuntingYard {
public:
void InputString();
void OutputString();
int precedence(char A, char B);
void ShuntingAlgorithm();
private:
std::string inString;
std::string outString;
std::stack<char> operatorStack;
std::stack<char> tokenStack;
};
#endif // SHUNTINGYARD_H
void InputString() {
std::cout << "Please enter an expression: ";
std::cin >> inString;
}
I'm sure I'll feel really dumb when I find/someone explains the solution, but I can't figure it out at the moment.

Answer 1

when you do -
void InputString() {
std::cout << "Please enter an expression: ";
std::cin >> inString;
}
It is only a bare function and it is not a member of the class ShuntingYard.
Hence it is not recognizing "instring"
So make InputString as a member of the class and then define it like below-
void ShuntingYard::InputString() {
std::cout << "Please enter an expression: ";
std::cin >> inString;
}
NOTE: Always write #endif //SHUTTINGYARD_H at the end of the file. It makes your code more standard.

Answer 2

Try adding the class name as well as the :: operator before the function's implementation:
void ShuntingYard::InputString() {
This tells the compiler that you are implementing a function called InputString() of the class ShuntingYard. Otherwise it thinks you are trying to declare a separate function that is separate from ShuntingYard, and thus does not know about its private variables.