void biggest_number() {
    float first_input;
    float big_num;
    float input;
    cout <<"\n You've chosen to Find out The Biggest Number. Type in number to compare\nType 0 if you want to stop the function.\nFirst number : ";

    cin >> first_input;
    first_input = big_num;
    //cout << first_input;

    while (1) {
        cin >> input;

        if (big_num < input) {
            input = big_num;
        }
        else if (input == 0) {
            cout << big_num;
            break;
        }
        else{
        }
    };
};

So I've written a function to find the biggest number. But whatever I put as an input, big_num always comes out as 0.

I've tried to use cout <<first_input << big_num; in order to find out where the function doesn't work. You can see from the comment. That part doesn't work and I couldn't figure out why.

CodePudding user response：

You have the assignment first_input = big_num; reversed. It should be big_num = first_input;

CodePudding user response：

float big_num;

You declare big_num but haven't assigned it a value, so big_num is uninitialized. So big_num can hold any value. Then, you assign first_input to equal big_num. So both first_input and big_num is holding random values.

It seems kind of strange to me that you input first_input, then immediately you assign first_input to equal big_num. I think that you meant the other way around.

big_num = first_input;

Also:

void biggest_number() {
    float first_input;
    float big_num;
    float input;
    cout <<"\n You've chosen to Find out The Biggest Number. Type in number to compare\nType 0 if you want to stop the function.\nFirst number : ";

    cin >> first_input;
    first_input = big_num;
    //cout << first_input;

    while (1) {
        cin >> input;

        if (big_num < input) {
            input = big_num;
        }
        else if (input == 0) {
            cout << big_num;
            break;
        }
        else{
        }
    }; // <-- here
}; // <-- and here

There is two unnecessary semicolons. You should remove it.

note: using namespace std; is bad practice, so avoid using it.

CodePudding user response：

void biggest_number()
{
    float first_input;
    float big_num;
    float input;
    cout <<"\n You've chosen to Find out The Biggest Number. Type in number to compare\nType 0 if you want to stop the function.\nFirst number : ";

    cin >> first_input;
    big_num = first_input;
    cout << "Second number :";
    

    while (1) 
    {
        cin >> input;

        if (first_input < input) 
        {
            big_num = input;
            cout<< big_num << "  Is the big number" << endl;
            break;
        }
        else if (input == first_input)
        {
            cout << "Both inputs are same" << endl;
            break;
        }
        else
        {
            cout<< big_num << "Is the big number" << endl;
            break;
        }
    }
}




int main()
{
    cout<<"Hello World";
    biggest_number();

    return 0;
}

CodePudding user response：

See @justANewbie's answer about the actual problem (mixing up your input and big_num variables).

I just wanted to provide a more compact solution. It's not important that the code is short in this case, but you might learn some more convenient C coding tricks/styles from it. Additionally, it's sometimes easier to spot errors when the code is compact and has less branching.

This solution uses a common C pattern you might call "read while":

#include <cmath> // for INFINITY
#include <iostream>

void biggest_number() {
    float biggest = -INFINITY;

    // while we can read a number and it's not zero
    for (float input; (std::cin >> input) && input != 0; ) {
        // keep track of biggest number found
        if (input > biggest) biggest = input;
    }

    std::cout << biggest;
}