Char array can hold more than expected

Question

I tried to run this code in C and expected runtime error but actually it ran without errors. Can you tell me the reason of why this happens?

char str[10];
sc         


        

Answer 1

As soon as you read or write from an array outside of its bounds, you invoke undefined behavior.

Whenever this happens, the program may do anything it wants. It is even allowed to play you a birthday song although it's not your birthday, or to transfer money from your bank account. Or it may crash, or delete files, or just pretend nothing bad happened.

In your case, it did the latter, but it is in no way guaranteed.

To learn further details about this phenomenon, read something about exploiting buffer overflows, this is a large topic.