Accessing consecutively numbered arrays

[hondgm]

This may be a long shot, but anyway... Say I have lots of arrays named list1[], list2[], list3[], etc. I want a while() loop or something similar where I do something like this:

 while(1) 
{    afunction(listX);
 }

....where X is incremented each time.
Is there a way to do this? I'm using GCC.


In case you wonder why I want to do this, I'm saving C arrays from Wireshark to feed into a C function for testing and the arrays it generates have incrementing numbers. I'm simply copy and pasting them, as-is, into my C file. The final target for the code is a small ARM processor, but I want to test my C function on a computer first so I don't care about code efficiency in this case.

Changing the syntax isn't really acceptable because I may have 100 of these arrays and it's very tedious to do this.

[hk_mp5kpdw]

Can you make all of those separate one-dimensional arrays into a single two-dimensional array? You could then loop through them much easier.

[hondgm]

Can you make all of those separate one-dimensional arrays into a single two-dimensional array? You could then loop through them much easier.

Well yes....but that means I have to reformat all the arrays. That's what I'm trying to avoid.

[Salem]

Do you have something like this?
char a1[100];
char a2[100];
char a3[100];

Are all your arrays the same type and length?

[hondgm]

Do you have something like this?
char a1[100];
char a2[100];
char a3[100];

Are all your arrays the same type and length?

Yes, yes, and no.

All type char, but not the same length unfortunately.

[anduril462]

So you have an array of char * and each element points to one of your different arrays:

char a1[17];
char a2[42];
char a3[100];

char *array_or_arrays[3] = {a1, a2, a3};

[oogabooga]

Note that you'll have to make the a1, a2, etc arrays global (or static).

#include <stdio.h>

char a1[100];
char a2[100];
char a3[100];

int main(void) {
    char *a[] = {a1,a2,a3};
    printf("%d\n", a[1][5]);
    return 0;
}

[anduril462]

Note that you'll have to make the a1, a2, etc arrays global (or static).

No, it will work if they're local, as long as they're in the same scope as, or an outer scope of, a. They simply must be valid whenever you're accessing them through a.

[oogabooga]

If I put the arrays inside main (and not static), I get the following warning (3 times on line 8 above):
[Warning] initializer element is not computable at load time

[laserlight]

If I put the arrays inside main (and not static), I get the following warning (3 times on line 8 above):

Then populate array_or_arrays element by element. Declaring the arrays global (or static) should be a result of other concerns, not the concern that the syntax for initialising array_or_arrays results in a compile warning. (EDIT: a quick test with gcc shows that this is probably a matter of C89 versus C99.)

[MK27]

a quick test with gcc shows that this is probably a matter of C89 versus C99.)

Really?

#include <stdio.h>

int main(int argc, const char *argv[]) {
	char list1[100], list2[100], list3[50],
		*p[3] = { list1, list2, list3 };
	return 0;
}

root~/C»gcc -Wall test.c
test.c: In function ‘main’:
test.c:5:4: warning: unused variable ‘p’

[laserlight]

Try:

gcc -Wall -pedantic -ansi test.c

versus:

gcc -Wall -pedantic -std=c99 test.c

[MK27]

pendantry.

If you can't use C99, this will work:

#include <stdio.h>

int main(int argc, const char *argv[]) {
	char list1[100], list2[100], list3[50],
		*p[3];
	
		p[0] = list1;
		p[1] = list2;
		p[2] = list3;

	return 0;
}

No warnings or errors with "gcc -Wall -pedantic -ansi".

[hondgm]

So you have an array of char * and each element points to one of your different arrays:

char a1[17];
char a2[42];
char a3[100];

char *array_or_arrays[3] = {a1, a2, a3};

Ok I tried this, by using Excel to create a list of numbers and using copy and paste tricks with my editor. Now I have another problem. I failed to mention that the size of each of these arrays is required. Normally I'd use sizeof, but this doesn't seem to work with pointers.

[oogabooga]

Just make a parallel array with the sizes.

int sizes[] = {17, 42, 100};