Loop in C help!

Question

My friends tell me that a special loop exists that isn't a 'while' loop or a 'do while' loop.

Does anyone know what it's called and the correct syntax for it's use?

Answer 1

There's the for loop, although I don't know how special I'd consider it.

Answer 2

A for loop maybe?

for (i = 0; i < 15; ++i) {
  /* do stuff */
}

Answer 3

you left out a for(;true;) loop

Answer 4

A goto loop perhaps? That is pretty special.

start:
       /* do stuff */
       if ( !done ) goto start;

Answer 5

There are 3 kind of loops in c.

The for loop: http://cprogramminglanguage.net/c-for-loop-statement.aspx

for (initialization_expression;loop_condition;increment_expression){
  // statements
}

The while loop: http://cprogramminglanguage.net/c-while-loop-statement.aspx

while (expression) {
  // statements
}

The do while loop: http://cprogramminglanguage.net/c-do-while-loop-statement.aspx

do {
  // statements
} while (expression);

And you can emulate loops with a function ofcourse:

Emulating a do while loop:

void loop(int repetitions){
    // statements
    if(repetitions != 0){
        loop(repetitions - 1);
    }
}

Emulating a while loop:

void loop(int repetitions){
    if(repetitions != 0){
        // statements
        loop(repetitions - 1);
    }
}

Answer 6

A setjmp loop perhaps? That is pretty special.

static jmp_buf buf;

int i = 0;
if ( setjmp(buf) < end ) {
    /* do stuff */
    longjmp(buf, i++);
} 

Answer 7

and don't forget recursion

void doSomething(int i)
{
    if(i > 15)
        return;
    /* do stuff */
    doSomething(i + 1);
}

Answer 8

My answer here could help you understand how C for loop works

Answer 9

A signal handler loop perhaps? That is pretty special.

#include <signal.h>

void loop(int signal)
{
    if ( !done ) {
        /* do stuff */
        raise(SIGINT);
    }
}

int main() {
    signal(SIGINT, loop);
    raise(SIGINT);
    return 0;
}

Answer 10

infinite loop ?

for(;;){ }

I like this one :-)

Answer 11

A Y combinator loop? That's special enough to be apple only (for now). Also special enough to leak memory all over the place

#include <stdio.h>
#include <Block.h>

typedef void * block;
typedef block (^block_fn)(block);
typedef void (^int_fn)(int);

int main(int argc, char ** argv) {
    block_fn Y = ^ block(block f) {
        return ((block_fn) ^ block(block_fn x) {
                return x(x);
            })(^ block(block_fn x) {
                    return ((block_fn)f)(Block_copy(^ block(block y) {
                                return ((block_fn)(x(x)))(y);
                            }));
                });
    };

    int_fn loop = Y(^ block(int_fn f) {
            return Block_copy(^ (int a) {
                    if (a <= 0) {
                        printf("loop done\n");
                    } else {
                        printf("loop %d\n", a);
                        f(a - 1);
                    }
                });
        });
    loop(10);

    return 0;
}