C While 循环问题

Question

我是 C 语言编码的新手。我试图让下面的项目运行，但它说我的程序在我输入第三个输入后停止工作。我不确定我选择对 all 或 bool 值使用 while 循环是解决这个问题的正确选择。我几乎觉得应该在程序的某处添加一个 if/else 语句。

我已经获得了该项目的流程图，基本上是这样的:

Get input values for inv1-4

While code !=-1

if code is !=1 proceed with loop and get input values for amounts bought/sold

else print inv1-4

#include <stdio.h>

int main(void)

{
    int inv1;
    int inv2;
    int inv3;
    int inv4;
    int amount_purchased;
    int amount_sold;

    printf("Please provide beginning inventory amounts in cases between 1 and 4.\n\n");
    printf("Enter the number of inventory for Piels (ID number 1): ");
    scanf("%d", &inv1);

    printf("\nEnter the number of inventory for Coors (ID number 2): ");
    scanf("%d", &inv2);

    printf("\nEnter the number of inventory for Bud (ID number 3): ");
    scanf("%d", &inv3);

    printf("\nEnter the number of inventory for Iron City (ID number 4): ");
    scanf("%d", &
          inv4);


    while (inv1 != -1 && inv2 != -1 && inv3 != -1 && inv4 != -1) {
            printf("\nEnter the number of cases of Piels (ID 1) purchased and sold this week.\n");
            printf("Amount purchased: \n");
            scanf("%d", &amount_purchased);
            printf("Amount sold: \n");
            scanf("%d", &amount_sold);
            inv1 = inv1 + amount_purchased - amount_sold;

            printf("\nEnter the number of cases of Coors (ID 2) purchased and sold this week.\n");
            printf("Amount purchased: \n");
            scanf("%d", &amount_purchased);
            printf("Amount sold: \n");
            scanf("%d", &amount_sold);
            inv2 = inv2 + amount_purchased - amount_sold;

            printf("\nEnter the number of cases of Bud (ID 3)purchased and sold this week.\n");
            printf("Amount purchased: \n");
            scanf("%d", &amount_purchased);
            printf("Amount sold: \n");
            scanf("%d", &amount_sold);
            inv3 = inv3 + amount_purchased - amount_sold;

            printf("\nEnter the number of cases of Iron City (ID 4) purchased and sold this week.\n");
            printf("Amount purchased: \n");
            scanf("%d", &amount_purchased);
            printf("Amount sold: \n");
            scanf("%d", &amount_sold);
            inv4 = inv4 + amount_purchased - amount_sold;



    }

    printf("Ending inventory is as follows.\n\n");

    printf("Piels (ID Number 1): %d \n", inv1);
    printf("Coors (ID Number 2): %d \n", inv2);
    printf("Bud (ID Number 3): %d \n", inv3);
    printf("Iron City (ID Number 4): %d \n", inv4);

    return 0;

}

Answer 1

我猜是这个问题

while (inv1 || inv2 || inv3 || inv4 != -1) 

是你写的不是你期望的。 (inv1 || inv2 || inv3 || inv4 != -1) 计算结果为真 inv1 不为 0，或 inv2 不为 0，或 inv3 不为0，或 inv4 不是-1。您可能想要的是，如果这些变量中的任何一个 为-1，循环必须结束。在这种情况下，正确的条件是:

while(inv2 != -1 && inv2 != -1 && inv3 != -1 && inv4 != -1)
{
    ...
}

请注意，在 bool 代数中 a && b 等同于 !a || !b。和一个|| b 等同于 !a && !b。

正如许多人在评论中所写的那样，您的 scanf 也是错误的。你必须 传递指向 int 的指针，而不是 int。所以不是

scanf("%d", amount_sold);

应该是

scanf("%d", &amount_sold);

这适用于您所有的 scanf 调用，否则它是未定义的行为 未定义行为的结果是未定义的。

编辑

我刚刚注意到您在循环末尾有一个无条件的 break。如果 你在第一次迭代中无论如何都要离开循环，你为什么要循环 首先？或者您是否忘记为 中断?