Are all char arrays automatically null-terminated?

c arrays string null-terminated
user1329846 picture user1329846 · Jun 27, 2012 · Viewed 26.5k times · Source

Probably I'm just too dump for googling, but I always thought char arrays get only null terminated by an literal initialization (char x[]="asdf";) and got a bit surprised when I saw that this seems not to be the case.

int main()
{
    char x[2];
    printf("%d", x[2]);
    return 0;
}

Output: 0

Shouldn't an array declared as size=2*char actually get the size of 2 chars? Or am I doing something wrong here? I mean it isn't uncommon to use a char array as a simple char array and not as a string, or is it?

Answer

K-ballo picture K-ballo · Jun 27, 2012

You are accessing an uninitialized array outside its bounds. That's double undefined behavior, anything could happen, even getting 0 as output.

In answer to your real question: Only string literals get null-terminated, and that means that char x[]="asdf" is an array of 5 elements.

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