Calculation is not producing the right result

[jwatson]

#include <stdio.h>
#include <conio.h>
#include <math.h>
 
main(){
int mark,num,pass=0,count;
float ppass;
printf("Please enter number of marks?:");
scanf("%d",&num);
 
for (count=0;count<num;count++)
{
printf("Enter mark%d:",count+1);
scanf("%d",&mark);
if (mark>=50)
pass++;
}
printf("%d",pass);
ppass=(float)(pass/num)*100.0;
printf("The passing rate of the class is : %.1f",ppass);
 
getch();
return(0);
}

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Why my percentage of passes(ppass) cant be calculated??? Theres not error when i compile but the computation is having error... it keep show 0.0......which is the incorrect answer.

[Banfa]

This line

ppass=(float)(pass/num)*100.0;

pass and num are both int so it is performing integer arithmatic. Since by definition pass < num the pass/num = 0 so ppass will always be 0.

To get the calculation to work cast to float before performing the division.