How does the use of the static keyword affect the scope and lifetime of local variables in a program?

The keyword static when declaring a local variable inside a function changes the variable's lifetime and scope.

• Scope: The variable remains local to the function, meaning it is only accessible within that function.
• Lifetime: The variable exists throughout the entire runtime of the program, not just during the function call.

This means that the value of such a variable is preserved between function calls.

Example:

#include <stdio.h>

void func() {
    static int count = 0; // initialized once
    count++;
    printf("Count: %d\n", count);
}

int main() {
    func(); // Count: 1
    func(); // Count: 2
    func(); // Count: 3
    return 0;
}

In this example, the variable count retains its value between calls to func thanks to static.