c - 在 C 中的多个函数之间传递不同的值？

Question

我在多个函数之间传递不同的值时遇到问题。也就是说，我试图让两个函数接受用户输入，然后将这两个输入传递给第三个函数，该函数计算这些输入的总和。之后，它将总数传递给另一个计算真实总数的函数。最后，在那之后，最后一个函数显示最终数字。我似乎无法弄清楚如何让多个函数通过。

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

int carLength(int userInput) //Length
{
int length = 0;
do
{
    printf("\nPlease input the length of the area being carpeted:");
    scanf("%d", &userInput);
} while (length = 0);
length = userInput; //Essentially using this to store user input so i can 
use it later.
return length;
}

int carWidth(int userInput) //Width
{
int width = 0;
do
{
    printf("\nPlease input the width of the area being carpeted:");
    scanf("%d", &userInput);
} while (width = 0);
width = userInput; //Same as width
return width;
}

int carCalculate(int cost) //cost
{
int width = userInput;
int cost = (width * length) * 20;
return cost;
}

float cardiscount(float discount) //discount
{
float discount = cost - (cost * .1);
return discount;
}

float displaydisc(float discount) //discount
{
printf("\nThe total cost is: %f\n", discount);
return discount;
}

int main()
{
int length = 0;
int width = 0;
int cost = 0;
int discount = 0;
do {
    length = carLength;
} while (length == 0);
    do {
        width = carWidth;
    } while (carWidth == 0);
    do {
        cost = carCalculate;
    } while (cost == 0);
    do {
        discount = cardiscount;
    } while (discount == 0);
    do {
        displaydisc;
    } while (discount > 0);
    printf("\n Thank you for using this program!");

system("pause");
}

Answer 1

有几个问题，

• 大多数汽车功能的参数都是无用的
• 未提供所需参数(carCalculate)
• = 0 上的循环有 =(赋值而不是等式测试)
• 在变量不变的条件下循环
• 在 main() 中调用函数而不使用 (param)

这段代码应该可以工作:

int carLength() // <== no need to provide length, it is returned
{
    int length;
    do
    {
        printf("\nPlease input the length of the area being carpeted:");
        scanf("%d", &length);
    } while (length == 0); // <== length is changed within the loop
    return length;
}

int carWidth() //Width
{
    int width = 0;
    do
    {
        printf("\nPlease input the width of the area being carpeted:");
        scanf("%d", &width);
    } while (width == 0);
    return width;
}

int carCalculate(int width, int length) // <== need to provide values
{
    int cost = (width * length) * 20;
    return cost;
}

float cardiscount(float cost) //discount
{
    float discount = cost - (cost * .1);
    return discount;
}

void displaydisc(float discount) //discount
{
    printf("\nThe total cost is: %f\n", discount);
}

int main()
{
    int length; // <== no need to set to 0, as their values
    int width;  //     are going to be initialized later
    int cost;
    int discount;

    length = carLength();

    width = carWidth();

    cost = carCalculate(width, length);

    discount = cardiscount((float)cost);

    displaydisc(discount);

    printf("\n Thank you for using this program!");

    system("pause");
}

您也可以要求输入函数填充一个值，该值将指针作为参数给出，例如

int carLength(int *length) {
    do {
        printf("\nPlease input the length of the area being carpeted:");
        scanf("%d", length);
    } while (*length == 0);
}

int 在 main 中调用

carLength( &length );