我如何在一个 if 语句中声明所有数字

Question

#include <iostream>

using namespace std;

int main () 
{
    int quantity;

again:
    cout<<"Enter the quantity: ";
    cin>>quantity;
    If(quantitiy == '1' )
    {
        total = quantity*price
    }
    else
    {
        goto again;
    }
    return 0;
}

How could I declare all the numbers in one if statement?

Answer 1

Pretty much everything in your code is wrong and needs fixing. Use a do..while loop instead of goto . Correct your typos on If and quantitiy . Declare and initialize the missing total and price variables. Add the missing ; on the total assignment. And '1' and 1 are two completely different types and values.

Try something more like this instead:

#include <iostream>

using namespace std;

int main () 
{
    int quantity;
    double price = ...; // for you to decide, unless you ask the user...
    double total = 0;

    do {
        cout << "Enter the quantity: ";
        cin >> quantity;
    }
    while (quantity != 1);

    total = quantity*price;

    return 0;
}

Of course, it really doesn't make sense to prompt the user for a quantity and then only accept 1 . You probably want something more like this:

#include <iostream>

using namespace std;

int main () 
{
    int quantity;
    double price = ...; // for you to decide, unless you ask the user...
    double total = 0;

    do {
        cout << "Enter the quantity (0 to stop): ";
        cin >> quantity;

        if (quantity == 0) break;

        total += (quantity * price);
    }
    while (true);

    return 0;
}