Program does nothing when run - c++

Question

This program is a very simple one, a guessing game, however the issue is that when I compile it, it displays no errors. When I run it, it does nothing. I have tried fixing it, in that I moved the code within the guess() function back into main, and that works, printing "Enter a number between 0 & 100: ". Then when you do enter a number, it freezes, and this is probably caused by the lack of stop condition for the recursion. As I am not returning integers, as main has to, I reverted back to using the guess() function, and I have no idea why it doesn't work.
#include <iostream>
#include <cstdlib>
#include <string>
int computer = rand() % 101;
int user = 0;
int counter = 0;
std::string guess();
int main(void) {
std::string guess();
return 0;
}
std::string guess() {
std::cout << "Enter a number between 0 & 100: ";
std::cin >> user;
if(!(std::cin >> user)) {
return "You entered a non-numeric. Try again. Tries will not be added.";
std::cin.clear();
std::cin.ignore(10000, '\n');
std::string guess();
}
else {
if(user == computer) {
std::cout << "You guessed the right number of " << computer << " in " << counter << " tries.\n";
}
else {
if(user < computer) {
return "The answer is higher. Try again.";
}
else if(user > computer) {
return "The answer is lower. Try again.\n";
}
counter++;
std::string guess();
}
}
}
Note that I am very much a novice programmer, and the issue is probably quite simple and obvious, but I just can't see it. Thanks.

Answer 1

The problem is, that your often write std::string guess(); in order to call your guess() method (e.g. in main. But that doesn't call the method. What it actually does is to declare a new function guess, which is never called (see also Most vexing parse). To only call the method simply write guess();, or auto result = guess(); if you actually want to use the return value.
Also there is an error in this part of your code (see comment):
if(!(std::cin >> user)) {
return "You entered a non-numeric. Try again. Tries will not be added.";
// the following lines are never executed, since you already returned.
std::cin.clear();
std::cin.ignore(10000, '\n');
std::string guess();
}

Answer 2

Issue
The issue is indeed simple and obvious:
std::string guess();
It's obvious that you would like to call your "guess" function, but instead you've just declared it inside "main" and inside "guess".
These declarations are similar to the declaration that you made on the next line after int counter = 0;. It tells compiler that if it encounters call to the function named "guess" it should know that it is a function that takes no arguments and returns std::string.
So, the issue is that instead of calling a function, you declared it several times;
Solution
When you want to call your function you should do it like this:
std::string result = guess();
But since you return some message from guess() I think you should add output after that:
std::cout << result << std::endl;
Actually, I think it would be better to remove return value altogether. In order to do that you should modify "guess" function in a following way:
change return type from std::string to void
replace return with std::cout <<.

Answer 3

Many mistakes.
Firstly you don't need string return type.
So change std::string guess() to void guess()
Then use cin.fail() instead of !(cin>>user)
Also use else if rather than
else{
if{
To generate random number, firstly intialize seed and that can't be done globally, so generate random number in main and pass it in guess function.
To summarize here is the code
#include <iostream>
#include <cstdlib>
#include <string>
#include<ctime>
int user = 0;
int counter = 0;
void guess(int computer);
int main(void) {
srand(time(NULL));
int computer = rand() % 101;
guess(computer);
return 0;
}
void guess(int computer) {
std::cout << "Enter a number between 0 & 100: ";
std::cin >> user;
//std::cout<<computer<<std::endl;
if(std::cin.fail()) {
std::cout<< "You entered a non-numeric. Try again. Tries will not be added.";
std::cin.clear();
std::cin.ignore(10000, '\n');
guess(computer);
}
else if(user == computer) {
std::cout << "You guessed the right number of " << computer << " in " << counter << " tries.\n";
return;
}
if(user < computer) {
std::cout<< "The answer is higher. Try again.\n";
}
else if(user > computer) {
std::cout<< "The answer is lower. Try again.\n";
}
counter++;
guess(computer);
}