Will a value live perpetually when there's no reference to it?

Question

Suppose the following minimal code:

#include <stdio.h>
char character = 'c';
int main (void)
{
    char character = 'b';
    printf("The current value of head is %c", character);
}

I overwrote character within main,
Then what happened to c? Will it be destroyed automatically or live in the memory perpetually?

This comment clicks with me: "variables in C are nothing but named chunks of memory".

Answer 1

"shadowing" the global character variable hides the variable from the main function, but it will still be a part of the program.

If character variable was declared as static, then the compiler might warn that character variable is never used and character will be optimized away.

However, character variable is not declared as static; the compiler will assume that character variable might be accessed externally and keep character variable in the memory.

EDIT:

As noted by @Deduplicator, linker optimizations and settings could omit the variable from the final executable, if permitted. However, this is an edge case that won't happen "automatically".

Answer 2

You have two separate variables named character: one at file scope set to 'c', whose lifetime is the lifetime of the program, and one in main set to 'b', whose lifetime is that of its scope.

The definition of character in main masks the definition at file scope, so only the latter is accessible.