Question

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Why does this integer division yield 0?

I have a C header file,which contains various constant values used in my project.The values are defined using #define (e.g. #define MAX_DATA_VAL 5).

When I use this value in another file for division,I get the wrong answer.

//- In file MyParameters.h
#define MAX_DATA_VAL  5
#define MIN_DATA_VAL -5



// - In file MyFunctions.c

#include "MyParameters.h"

void Function()
{
   float temp = 0;

   temp = 2/MAX_DATA_VAL;  // Wrong Output
}

The value of temp remains 0 (checked while debugging).However if I did:

temp     = 0;
float a  = MAX_DATA_VAL;

temp = 2/MAX_DATA_VAL;  // Correct Output

I get the right answer!!…Could anyone please explain what’s happening…

Thanks in advance 🙂

Answer 1

MAX_DATA_VAL is being treated as an integer and thus your division was doing integer division (rounds down to nearest whole number). To make sure it knows it’s a float, do:

#define MAX_DATA_VAL 5.0f