Objective-c – How to break out of two nested for loops in Objective-C

cloopsobjective c

I have two for loops nested like this:

for(...) {
    for(...) {

    }
}

I know that there is a break statement. But I am confused about if it breaks both loops or just the one in which it was called? I need to break both ones as soon as I see that it doesn't make sense to iterate more times over.

Best Answer

If using goto simplifies the code, then it would be appropriate.

for (;;) 
{
    for (;;) 
    {
        break; /* breaks inner loop */
    } 
    for (;;) 
    {
        goto outer; /* breaks outer loop */
    }
} 
outer:;

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Python – Accessing the index in ‘for’ loops

Using an additional state variable, such as an index variable (which you would normally use in languages such as C or PHP), is considered non-pythonic.

The better option is to use the built-in function enumerate(), available in both Python 2 and 3:

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Check out PEP 279 for more.

What REALLY happens when you don’t free after malloc

Just about every modern operating system will recover all the allocated memory space after a program exits. The only exception I can think of might be something like Palm OS where the program's static storage and runtime memory are pretty much the same thing, so not freeing might cause the program to take up more storage. (I'm only speculating here.)

So generally, there's no harm in it, except the runtime cost of having more storage than you need. Certainly in the example you give, you want to keep the memory for a variable that might be used until it's cleared.

However, it's considered good style to free memory as soon as you don't need it any more, and to free anything you still have around on program exit. It's more of an exercise in knowing what memory you're using, and thinking about whether you still need it. If you don't keep track, you might have memory leaks.

On the other hand, the similar admonition to close your files on exit has a much more concrete result - if you don't, the data you wrote to them might not get flushed, or if they're a temp file, they might not get deleted when you're done. Also, database handles should have their transactions committed and then closed when you're done with them. Similarly, if you're using an object oriented language like C++ or Objective C, not freeing an object when you're done with it will mean the destructor will never get called, and any resources the class is responsible might not get cleaned up.

Best Answer

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