What is the use of static variables? I cannot understand the uses of it clearly.

Question

#include <stdio.h>

void say_hello();

int main() {
int i;

for (i = 0; i < 5; i++) {
say_hello();
}

return 0;
}

void say_hello() {
static int num_calls = 1;

printf("Hello number %d\n", num_calls);
num_calls++;

}

Answer 1

Static variable value will be initialized only ones in total program, and can shared same value throughout the program with current changes...

Observe the behavior of num_calls values in your program with static, with out static...
You will find the difference..

Answer 2

Static variable retain it's value during function calls.
So making a call to that function will result in updated values of the static variable.