COMP1511 17s1 Code Examples from Lectures on extra_C Introduction to Programming
global.c 
#include <stdio.h>

int x;

void f(int j) {
    x = j;
}

int main(void) {
    printf("%d\n", x); // prints 0
    f(42);
    printf("%d\n", x); // prints 42
    x = 1;
    printf("%d\n", x); // prints 1
    return 0;
}
static.c 
#include <stdio.h>

int f(int j) {
    static int x;
    x = x + j;
    return x;
}
int main(void) {
    printf("%d\n", f(1)); // prints 1
    printf("%d\n", f(2)); // prints 3
    printf("%d\n", f(4)); // prints 7
    return 0;
}
cast.c 
#include <stdio.h>

int main(void) {
    int x = 42;
    int y = 11;
    double f;

    f = x / y;
    printf("42/11=%f\n", f); // prints 3.000000
    f = x/((double)y);       // convert y to a double
    printf("42/11=%f\n", f); // prints 3.818182
    return 0;
}