Circumference

#include <stdio.h>

int main() {
    int diameter;
    //note the comma at the end
    const double PI = 22/7.0; //use this PI value
    /**Note This also works:
    const double PI = 22.0/7
    const double PI = 22.0/7.0
    */

    printf("Input diameter: ");
    scanf("%d", &diameter); //get the radius of the cylinder

    printf("PI: %lf\n", PI); //Output the value for PI(22/7)

    double circumference = PI*diameter; //calculate the circumference
    printf("Circumference: %lf\n", circumference); //output the result
}