Dynamic jump to label in C

Question

I would like to display the output - numbers 1 to 5, followed by 4-5 infinitely. Is there any way i can pass the value of i(4) instead of the character i in goto1. Or is the

Answer 1

Since you want to do this the wrong (aka. creative) way, have you considered trampolining?

#include 

typedef void (*generic)(void);
typedef generic (*continuation)(void);

generic first(void);
generic second(void);

int main(void) {
    continuation fubar = first;
    for (;;) {
        fubar = (continuation) fubar();
    }
}

generic first(void) {
    printf(" num is 1 \n"
           " num is 2 \n"
           " num is 3 \n");
    return (generic) second;
}

generic second(void) {
    printf(" num is 4 \n"
           " num is 5 \n");
    return (generic) second;
}

Continuing on from the idea of using function pointers (see what I did there? Giggity!), you could use an array of function pointers:

#include 

typedef size_t (*function)(size_t);

size_t first(size_t);
size_t second(size_t);

int main(void) {
    function function[] = { first, first, first, first, second };
    size_t index = 0;

    for (;;) {
        index = function[index](index);
    }
}

size_t first(size_t index) {
    printf(" num is %d \n", ++index);
    return index;
}

size_t second(size_t index) {
    printf(" num is %d \n", index+1);
    return index-1;
}