c - Why does this assignment break my program? -

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i learning c , i'm not sure how phrase this, why uncommenting line 11 in following code break program? 

#include <stdio.h>  int main(int argc, char *argv[]) {     printf("argc: %d\n", argc);      char *states[] = {};     int = 0;     while(i < argc) {         printf("arg %d: %s\n", i, argv[i]);         //states[i] = "test";           i++;     }       return 0; }

when uncomment line , run program this:

greggery@lubu:~/code$ ./myprog aaa bbb ccc argc: 4 arg 0: ./lc arg 1: aaa

why states[i] = "test"; breaking while loop? when comment out see arguments printed.

it breaks because array states empty. make size of argc (that's allowed in c99) fix problem:

char *states[argc];

the reason follows: char *states[] = {}; makes array of 0 elements, dereference states[i] undefined behavior.


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