What does "for(;;)" do in C#?

Question

I've seen this on occasion in books I've read. But I've found no explanation.

for (;;)
{
  // Do some stuff.
}

Is it kind of like "while(true)"? Basically an endless loop for polling or something? Basically something you'd do until you intentionally break the loop?

Answer 1

Is it kind of like "while(true)"?

Yes. It loops forever.

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Also note the comment by Andrew Coleson:

Languages like C don't have built-in boolean primitives, so some people prefer for(;;) over while(1)

Answer 2

Loop forever.

Answer 3

You are correct. This is a common C# idiom for an endless loop.

Answer 4

Yes, It is an infinite loop.

Answer 5

Yes, it's an infinite loop. Same idea/effect as doing while(true) { ... }

Answer 6

Yes.

In a for if nothing is provided:

• The initialisation does nothing.
• The condition is always true
• The count statement does nothing

It is equivalent to while(true).

Answer 7

Inifinite loop like saying

while (0<1)

Answer 8

Yes, it's an endless loop, just like while(true).

It's the slightly preferred convention, probably because it's shorter. There's no efficiency difference at all.

Answer 9

To be precise, any for loop without anything between the semicolons will loop forever (until terminated by some other means), because it has no defined invariant.

Answer 10

Correct. Note that the braces of a for loop contain three parts:

1. Initialization code
2. A condition for continuing the loop
3. Something that gets executed for each loop iteration

With for(;;), all of these are empty, so there is nothing done to initialize the loop, there is no condition to keep it running (i.e. it will run indefinitely) and nothing that gets executed for each iteration except the loop's content.

Answer 11

If I recall correctly it's use over "while(true)", is it more resembles "for(;;) //ever"

Answer 12

It doesn't have an end condition, so it will loop forever until it find a break, as you already guessed.

Answer 13

Yes! .

Answer 14

Take a look at a for loop.

for ( initialization ; condition ; increment  )

1) initialization - set a counter variable here
2) condition - keep looping until the counter variable meets the condition
3) increment - increment the counter

If there is no condition, a loop will go on forever. If it does such, then there is no need for a counter. Therefore

for(;;)

Answer 15

Often used in embedded programming.

-setup interrupts and timers. -then loop forever.

When an interrupt or timer occurs that will be handled.

Answer 16

I might also add that it looks like 2 smiley faces winking at you

for (; ;)

maybe that's why some people like to use it.

Answer 17

Yes, it loops forever. But the reason why you should use

for(;;)

instead of

while(true)

is that

while(true)

will give you a compiler warning "conditional expression constant", while the for-loop does not. At least you'll get such a compiler warning in the highest warning level.