Breaking Out of a Nested Loop

How to break out of nested loops?

Use:

if (condition) {
    i = j = 1000;
    break;
}

How do I break out of nested loops in Java?

Like other answerers, I'd definitely prefer to put the loops in a different method, at which point you can just return to stop iterating completely. This answer just shows how the requirements in the question can be met.

You can use break with a label for the outer loop. For example:

public class Test {
    public static void main(String[] args) {
        outerloop:
        for (int i=0; i < 5; i++) {
            for (int j=0; j < 5; j++) {
                if (i * j > 6) {
                    System.out.println("Breaking");
                    break outerloop;
                }
                System.out.println(i + " " + j);
            }
        }
        System.out.println("Done");
    }
}

This prints:

Breaking out of a nested loop

Well, goto, but that is ugly, and not always possible. You can also place the loops into a method (or an anon-method) and use return to exit back to the main code.

    // goto
    for (int i = 0; i < 100; i++)
    {
        for (int j = 0; j < 100; j++)
        {
            goto Foo; // yeuck!
        }
    }
Foo:
    Console.WriteLine("Hi");

vs:

// anon-method
Action work = delegate
{
    for (int x = 0; x < 100; x++)
    {
        for (int y = 0; y < 100; y++)
        {
            return; // exits anon-method
        }
    }
};
work(); // execute anon-method
Console.WriteLine("Hi");

Note that in C# 7 we should get "local functions", which (syntax tbd etc) means it should work something like:

// local function (declared **inside** another method)
void Work()
{
    for (int x = 0; x < 100; x++)
    {
        for (int y = 0; y < 100; y++)
        {
            return; // exits local function
        }
    }
};
Work(); // execute local function
Console.WriteLine("Hi");

How can I break out of multiple loops?

My first instinct would be to refactor the nested loop into a function and use return to break out.

Breaking out of nested loops

It has at least been suggested, but also rejected. I don't think there is another way, short of repeating the test or re-organizing the code. It is sometimes a bit annoying.

In the rejection message, Mr van Rossum mentions using return, which is really sensible and something I need to remember personally. :)

When breaking out of a nested loop, how do I make it so that the inner loop isn't ignored in Python?

The way you have it written right now, the inner loop will always break on the first iteration (when i = 0). This is why you are only seeing it print once, the outer loop is looping 5 times, however the inner loop only ever gets through the first iteration before hitting break.

See below, the break line should be nested inside the if statement so it only breaks from the inner loop when the two numbers match.

for i in range(5):
    for j in range(5):
        if i == j:
            print('Same Number')
            break