Question

每当我运行我的代码时，变量bookcost会将自身更改为值：3435973836。

它到达processingData函数后执行此操作。我不知道为什么一直这样做！我已经编写了这个没有函数的程序，它工作正常:(这是我的第二个编程课程，它是在线的，几乎没有教授的支持。

#include <stdio.h>

void inputData(int* inputs,int* booknmbr, int* nmbrpurchased, int* bookcost);
void processingData(int bookcost, int nmbrpurchased, int totalpurch, int costaccu);
void outputInfo(int booknmbr, int nmbrpurchased, int bookcost, int* total);

    int bookcounter = 0;
    int totalpurch = 0;
    int costaccu = 0;
    int totalcostaccu = 0;


int main ()

{
    int booknmbr;
    int nmbrpurchased;
    int bookcost; 
    int bookcounter = 0;
    int cycleRun;
    int total;
    int inputs;

    printf("Run Program? 1 for Yes or -1 for No \n"); // ask user to input product name
    scanf("%d", &cycleRun);
    while (cycleRun != -1) 
    {

        inputData(&inputs, &booknmbr, &nmbrpurchased, &bookcost);
        processingData(bookcost, nmbrpurchased, totalpurch, costaccu);
        outputInfo(booknmbr, nmbrpurchased, bookcost, &total);

        printf("Run Program? 1 for Yes or -1 for No \n"); // ask user to input product name
        scanf("%d", &cycleRun);
    }
}

void inputData(int* inputs, int* booknmbr, int* nmbrpurchased, int* bookcost)
{
    printf( "\nEnter the Book Product Number?\n" );
    scanf("%d", &booknmbr);

    printf( "Enter the Number of Books Purchased?\n" );
    scanf("%d", &nmbrpurchased);

    printf( "Enter the Cost of the Book Purchased?\n");
    scanf("%d", &bookcost);

    printf( "TEST: %u\n", bookcost);

    return;
}

void processingData(int bookcost, int nmbrpurchased, int totalpurch, int costaccu)
{
    int total;

    printf( "TEST: %u\n", bookcost);

    total = bookcost * nmbrpurchased;
    totalpurch = totalpurch + nmbrpurchased;
    costaccu = costaccu + bookcost;
    totalcostaccu = totalcostaccu + (bookcost * nmbrpurchased);

    printf( "TEST: %u\n", bookcost);

    return;
}

void outputInfo(int booknmbr, int nmbrpurchased, int bookcost, int* total)
{
    printf( "\nBook Product number entered is: %u\n", booknmbr);
    printf( "Quantity of Book Purchased is: %u\n", nmbrpurchased);
    printf( "Cost of the Book Purchased is: %u\n", bookcost);
    printf( "Total cost of books is: $%u\n", total);

    return;
}

void outputSummary(int bookcounter, int totalpurch, int costaccu, int totalcostaccu)
{
    printf( "\n\nNumber of records processed = %u\n", bookcounter);
    printf( "Number of books purchased = %u\n", totalpurch);
    printf( "Cost of the books purchased = $%u\n", costaccu);
    printf( "Total cost for all book purchases = $%u\n", totalcostaccu);

    return;
}

Answer 1

快速搜索显示3435973836是Windows在x64上提供未分配内存的值 - 这是有道理的，因为它表明你有指向无处的指针。

让我们看看这里发生了什么。在main()中，您定义了一堆整数。当您说inputData(&inputs, &booknmbr, &nmbrpurchased, &bookcost)时，您会将引用传递给这些整数。该函数的签名为void inputData(int* inputs, int* booknmbr, int* nmbrpurchased, int* bookcost) - 到目前为止一直很好。

...然后你scanf("%d", &booknmbr)。想想这一秒。

没错。您将scanf()引用指向要填充的整数的指针，而不仅仅是指针。这是一个容易陷入的陷阱，因为你可能总是以scanf()的方式拨打这样的电话＆amp;它变成了习惯。用scanf("%d", booknmbr)取代它会让世界再次成为现实。

Answer 2

您将变量的地址传递给inputData ...试试这个：

/* not using inputs? */
void inputData(int* pinputs, int* pbooknmbr, int* pnmbrpurchased, int* pbookcost)  {
    printf( "\nEnter the Book Product Number?\n" );
    scanf("%d", pbooknmbr);
    printf( "Enter the Number of Books Purchased?\n" );
    scanf("%d", pnmbrpurchased);
    printf( "Enter the Cost of the Book Purchased?\n");
    scanf("%d", pbookcost);
    printf( "TEST: %u\n", *pbookcost);
}

total中的outputInfo存在类似问题。您需要仔细阅读代码并注意细节，注意哪些变量是指针，哪些是标量值。正如我在这里所做的那样，以不同的方式命名指针是有帮助的。

我的变量不断将其值更改为3435973836

2 个答案: