What does the value of a not valued variable represents?

[Laythe]

Greetings EveryOne

What does the value of a not valued variable represents?

Isn't it a null variable, shouldn't a null variable be equal to 0?

#include <stdio.h>

int main()
{
    int x;

    printf("x = %d\n", x);
    
    return 0;
}

Thanks In Advance

[Salem]

If you have an uninitialised variable, then all bets are off as to what you get.
- it might be zero (consistently)
- it might be non-zero (consistently)
- it might be random (over a small set of values)
- it might be truly random (or seem so)
- it might just crash your program.

Doing absolutely anything (adding more code, changing your compiler, changing your compiler flags) can make anything else happen.

[rags_to_riches]

Read the FAQ

[Laythe]

According to C FAQ :

Variables with automatic duration (i.e. local variables without the static storage class) start out containing garbage, unless they are explicitly initialized. (Nothing useful can be predicted about the garbage.)

what do you advice me to do, especially when declaring arrays as they might be long or moderately long?

[CommonTater]

what do you advice me to do, especially when declaring arrays as they might be long or moderately long?

Initialize them correctly....

int main (void)
  {
     int x = 0;   // single variable
     int y = 42; 

     int a[10] = {0};  // array
     int b[43] = {-1};

     // etc.
    return 0; 
}