Question

我刚刚开始编程，所以我知道这可能是一个非常基本的错误，但我一直试图找出如何修复我的代码中的逻辑错误，以便从哈佛大学的CS50课程中获得greedy.c，但没有成功。我已经找到了问题的解决方案，但他们似乎都以与我尝试不同的方式解决了问题。我已经对其他示例进行了逆向工程，现在我对它们有所了解，但我真的想知道如何使我自己的版本运行良好。

我试图通过一系列while循环来完成问题，每个循环从总欠款中减去某个硬币值，并在总硬币数上加一个硬币。对我来说，似乎逻辑上它是有道理的，但是当我运行程序时，它并没有给我预期的输出。它只是不在底部执行printf语句。我希望你们其中一个人能够帮我一臂之力！谢谢你的帮助！

继承我的代码：

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

int main (void)
{
    printf("How much change is needed?\n");
    float owed = get_float();
    int coins = 0;
    /*While loops subtracting one coin from change owed, and adding one to coin count*/
    while (owed >= 0.25)
    {
        owed = owed - 0.25;
        coins = coins + 1;
    }
    while (owed >= 0.1)
    {
        owed = owed - 0.1;
        coins = coins + 1;
    }
    while (owed >= 0.05)
    {
        owed = owed - 0.05;
        coins = coins + 1;
    }
    while (owed >= 0.01)
    {
        owed = owed - 0.01;
        coins = coins + 1;
    }
    /*While loops done, now print value of "coins" to screen*/
    if (owed == 0)
    {
        printf("You need %i coins\n", coins);
    }
}

编辑：

所以我多玩了一下，并完成了“if”声明。它为我返回错误，那么程序结束时“欠”的值如何不等于0？

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

int main (void)
{
    printf("How much change is needed?\n");
    float owed = get_float(); //Gets amount owed from user in "x.xx" format
    int coins = 0; //Sets initial value of the coins paid to 0
    //While loops subtracting one coin from change owed, and adding one to coin count
    while (owed > 0.25)
    {
        owed = owed - 0.25;
        coins = coins + 1;
    }
    while (owed > 0.1)
    {
        owed = owed - 0.1;
        coins = coins + 1;
    }
    while (owed > 0.05)
    {
        owed = owed - 0.05;
        coins = coins + 1;
    }
    while (owed > 0.01)
    {
        owed = owed - 0.01;
        coins = coins + 1;
    }
    //While loops done, now print value of "coins" to screen
    if (owed == 0)
    {
        printf("You need %i coins\n", coins);
    }
    else
    {
        printf("Error\n");
    }
}

编辑：

所以一旦我的代码工作，我开始摆弄它和过度工程。继续最后（现在）版本！

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



int main (void)
{
    srand(time(0));                                             //generates random seed
    float price = round(rand()%500);                            //generates random price between 0 and 500 cents
    printf("You owe %f. How much are you paying?\n", price/100); //shows user their price between 0 and 5 dollars
    printf("Dollars: ");
    float paymnt = get_float()*100;                             //gets the amount user will pay in dollars then converts to cents

    int owed = round (paymnt - price);                         //calculates the change owed by paymnt-price
    int coins = 0;                                              //Sets initial value of the coins paid to 0
    int quarters= 0;
    int dimes = 0;
    int nickels = 0;
    int pennies = 0;

    if (owed ==0 && price >0)                                   //If someone pays in exact
    {
        printf("You paid the exact amount!\n");
    }
    else if (owed < 0)                                          //If someone doesn't pay enough
    {
        printf("You didn't give us enough money!\n");
    }
    else                                                        //Else(We owe them change)
    {
        printf("Your change is %i cents\n", owed);
        //While loops subtracting one coin from change owed, and adding one to coin count
        while (owed >= 25)
        {
            owed = owed - 25;
            quarters = quarters + 1;
        }
        while (owed >= 10)
        {
            owed = owed - 10;
            dimes = dimes + 1;
        }
        while (owed >= 5)
        {
            owed = owed - 5;
            nickels = nickels + 1;
        }
        while (owed >= 1)
        {
            owed = owed - 1;
            pennies = pennies + 1;
        }
        //While loops done, now print each coin and total coins needed to screen
        if (owed == 0)
        {
            coins = quarters + dimes + nickels + pennies;
            printf("You need %i coins (%i quarters, %i dimes, %i nickels, and %i pennies)\n", coins, quarters, dimes, nickels, pennies);
        }
        else
        {
            printf("Error\n");
        }
    }
}

Answer 1

您无法将浮点数与整数（0）进行比较，因为某些深层装配机制

你能做什么：

只需{无条件<{1}}
待办事项
```
printf("You need %i coins\n", coins)
```
这实际上是一种很常见的做法

Answer 2

谢谢大家的帮助。我最终遵循了Tardis的建议，并使用整数进行计算。这是成功的！这是我最终得到的代码：

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

int main (void)
{
    printf("How much change is needed?\n");
    float tmp = get_float() * 100;//Gets amount owed from user in "x.xx" format
    int owed = round(tmp);
    int coins = 0; //Sets initial value of the coins paid to 0
    //While loops subtracting one coin from change owed, and adding one to coin count
    while (owed >= 25)
    {
        owed = owed - 25;
        coins = coins + 1;
    }
    while (owed >= 10)
    {
        owed = owed - 10;
        coins = coins + 1;
    }
    while (owed >= 5)
    {
        owed = owed - 5;
        coins = coins + 1;
    }
    while (owed >= 1)
    {
        owed = owed - 1;
        coins = coins + 1;
    }
    //While loops done, now print value of "coins" to screen
    if (owed == 0)
    {
    printf("You need %i coins\n", coins);
    }
    else
    {
        printf("Error\n");
    }
}

喜欢最终获得正确程序的感觉。只是希望我能够自己想出这个：/尽管如此，感谢大家的建议。

新程序员，我在哈佛CS50的greedy.c上需要帮助

2 个答案: