CODEWITHSUNDEEP
cdivisiontruncate
Roni Castro
Roni Castro

Reputation: 2144

Division gives wrong answear

This is a simple problem of calculating the min number of coins needed to give the change, given a N value. The division 0.04/0.01 gives 3, why?

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int MinQtdCoins(float N, float coins[], int qtdCoins)
{
    int i, qtdMinCoins = 0;
    int numCoins=0;
    for(i=0; i<qtdCoins; i++)
    {
        if(N > coins[i] || fabs(N - coins[i]) < 0.0000000001)  // N >= coins[i]
        {
            numCoins = (int)(N/coins[i]);
            printf("Number of Coins: %f divided by %f = %d, ",N,coins[i],numCoins);
            qtdMinCoins += numCoins;
            N = N - numCoins*coins[i];
            printf("remains: %f\n",N);

        }
    }
    return qtdMinCoins;
}

int main()
{
    int qtdCoins = 5;
    float coins[] = {0.50, 0.25, 0.10, 0.05, 0.01};
    float N=9.79;

    printf("\n\n%d\n",MinQtdCoins(N, coins, qtdCoins));
    return 0;
}

Upvotes: 0

Views: 332

Answers (2)

&#181;tex
&#181;tex

Reputation: 908

you are doing floating point division and keeping the value in an integer...because of this value is truncated to 3

Upvotes: 0

AlexD
AlexD

Reputation: 32576

The division 0.04/0.01 gives 3, why?

numCoins = (int)(N/coins[i]);

Casting to int just truncates fractional part. So if 0.04/0.01 == 3.999.. (due to rounding), the result is 3.

Upvotes: 5

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