Simple input-output, keeps returning $0.00000

[adalta]

I wrote a simple code to calculate the total cost of gas for a week.

#include <stdio.h>

int main () {

#define MILES_PER_GALLO N 23;
#define MILES_TO_SCHOOL 25;

double cost_per_gallon ;
double trips;

printf("How much does gas cost this week?\n");
scanf("%lf", &cost_per_gallo n);

printf("How many times does John have to drive to campus this week?\n");
scanf("%lf", &trips);
trips = trips * 2;

double miles = MILES_TO_SCHOOL * trips;
double gallons = miles / MILES_PER_GALLO N
double cost = cost_per_gallon * gallons;

printf("John must spend $%lf on gas this week.\n", &cost);
}


upon compiling and running it, the final print gives "John must spend $0.00000 on gas this week."

Why?

[weaknessforcats]

In your printf statement you specify &cost. That would be the address of cost. You want just cost.

You would use &cost in scanf to place a value in cost.

[Rabbit]

Also missing semicolon after deceleration of gallons

[weaknessforcats]

It turns out that the semi-colon is supplied by the macro.

[donbock]

Suggest you remove the semicolons from the two macro definitions. That will require you to add a semicolon to the gallons assignment.

This has the benefit of removing semicolon from middle of miles assignment.