为什么我的程序对某些测试正确运行，而对其他测试却不正确？ [英] Why my program works correctly for some tests and not for others?

问题描述

这是我测试的结果：

:) greedy exists

:) greedy compiles

:( input of 0.41 yields output of 4
    expected "4\n", not "3\n"

:( input of 0.01 yields output of 1
    expected "1\n", not "0\n"

:) input of 0.15 yields output of 2

:) input of 1.6 yields output of 7

:) input of 23 yields output of 92

:) input of 4.2 yields output of 18

:) rejects a negative input like -.1

:) rejects a non-numeric input of "foo"

:) rejects a non-numeric input of ""

这是代码：

#include <stdio.h>
#include <cs50.h>

void count_coins();

int coin = 0;
float change = 0;

int main(void)
{
    do
    {
    change = get_float("How much change is owed? ");
    }
    while (change < 0);

    count_coins();

    printf("%i\n", coin);
}

void count_coins()
{
    while (change > 0.24)
    {
        coin++;
        change -= 0.25;
        // printf("%.2f\n", change);
    }

    while (change > 0.09)
    {
        coin++;
        change -= 0.10;
        // printf("%.2f\n", change);
    }

    while(change > 0.04)
    {
         coin++;
         change -= 0.05;
         // printf("%.2f\n", change);
    }

    while (change >= 0.01)
    {
        coin++;
        change -= 0.01;
        // printf("%.2f\n", change);
    }
}

推荐答案

As Havenard已经写道，问题在于更改被存储为 float 。
对于这样的程序，更改必须存储为整数值。

As Havenard already wrote, the problem is that change was stored as float. For such a programm change must be stored as an integer value.

此代码与 int 而不是 float ：

#include <stdio.h>
#include <cs50.h>

void count_coins (void);

int coin = 0;
int change = 0;

int main (void) {
    do {
        change = 41; // insert a get integer function here
    } while (change < 0);

    count_coins();

    printf("%i\n", coin);
}

void count_coins (void) {
    while (change >= 25) {
        coin++;
        change -= 25;
    }

    while (change >= 10) {
        coin++;
        change -= 10;
    }

    while(change >= 5) {
        coin++;
        change -= 5;
    }

    while (change >= 1) {
        coin++;
        change -= 1;
    }
}

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