Why Doesn't Array Bounds Violation Always Cause a Segmentation Fault in C ?

Exploring the Enigma of Array Bounds Violation

One may encounter an unexpected situation when accessing memory beyond the boundaries of an array. This raises the question, why does such access not trigger a segmentation fault?

Consider the following C code:

int main()
{
    int *a = new int[2];
    // int a[2]; // even this is not giving error
    a[0] = 0;
    a[1] = 1;
    a[2] = 2; // Accessing memory beyond the array bounds
    a[3] = 3; // Further access beyond the array bounds
    a[100] = 4; // Attempting to access memory far beyond the bounds
    int b;

    return 0;
}

Contrary to expectations, the code compiles without errors. This occurs because the behavior of such memory access is deemed "undefined" by the C standard. In effect, it means that anything can happen. One may be fortunate in instances where no errors occur, but this false sense of security can mask potential bugs in the code.

Therefore, it is crucial to avoid accessing memory beyond the declared bounds of an array. While such violations may not always lead to immediate errors, they can introduce unpredictable behaviors and compromise the reliability of the program.

The above is the detailed content of Why Doesn't Array Bounds Violation Always Cause a Segmentation Fault in C ?. For more information, please follow other related articles on the PHP Chinese website!