Help: why does it keep showing a wrong number?

I'm a beginner at C so I don't understand why my "False Positives" keep printing a large negative number?
Am I doing something wrong? Please help!

Code:

---

#include "stdio.h"

float falsePositive (float accuracy, float incidence, int population);




void question();


int main()
{
    printf("QUESTION 1\n");   
    question();


    return 0;
}




void question()
{
float accuracy, incidence;
int population;


    printf ("Enter population size:");
    scanf ("%d", &population);


    printf ("Enter the accuracy of the test as a percentages (e.g. 99):");
    scanf ("%f", &accuracy);


    printf ("Enter the incidence of the disease as a decimal fraction (e.g. .0001):");
    scanf ("%f", &incidence);


    printf("Population = %d, accuracy = %.2f, incidence = %.5f, False Positives = %.0f\n", population, accuracy, incidence, falsePositive(accuracy, incidence, population));
}




float falsePositive (float accuracy, float incidence, int population)
{
    float falsepositives, healthypeople;
    healthypeople = (population * (1-incidence));
    falsepositives = (healthypeople * (1-accuracy));


    return falsepositives;
}

---

this may b due to %.0f for falsepositive !!!
try using %.1f

Are you sure you're inputting the right percentage?

Code:

---

$ ./a.out
QUESTION 1
Enter population size:1000000
Enter the accuracy of the test as a percentages (e.g. 99):.95
Enter the incidence of the disease as a decimal fraction (e.g. .0001):.0001
Population = 1000000, accuracy = 0.95, incidence = 0.00010, False Positives = 49995
$ ./a.out
QUESTION 1
Enter population size:1000000
Enter the accuracy of the test as a percentages (e.g. 99):95
Enter the incidence of the disease as a decimal fraction (e.g. .0001):0.0001
Population = 1000000, accuracy = 95.00, incidence = 0.00010, False Positives = -93990600

---

In other words, do you need to pre-divide your percentage by 100 to express it as a fraction between 0 and 1 ?

Ahh! Finally it works!! Thanks so much for your help, Salem!! :biggrin::biggrin::biggrin: