c - 如何在结构中打印变量？

Question

#include <stdio.h>
#include <math.h>
#define G 9.81

typedef struct
{
    double weight;
    double drag;
    double time;
} USER_INPUT;

double calculateVelocity(USER_INPUT);

int main(int argc, char **argv)
{
    USER_INPUT userInput;
    double velocity;

    printf("Please enter weight, drag and time: ");
    scanf("%lf %lf %lf", &userInput.weight, &userInput.drag, &userInput.time);

    velocity = calculateVelocity(userInput);

    printf("At t = %f , the parachutist with weight %d kg\nand a drag coefficient %8.2f kg/s \n will have a velocity of %8.2f m/s^2", &userInput.time, &userInput.weight, &userInput.drag, velocity);

    return 0;
}

double calculateVelocity(USER_INPUT data)
{
    double velocity;
    // TODO compute velocity
    return velocity;
}

在主函数中，我想显示结果。 如何打印结构中定义的变量？ 我尝试了 %f，它返回 0.000000，而 %d 返回一个随机数。

Answer 1

你在打印时犯了错误，

请注意'&'用于获取任何变量的地址，而不是值。所以当你打印时:

printf("At t = %f , the parachutist with weight %d kg\nand a drag coefficient %8.2f kg/s \n will have a velocity of %8.2f m/s^2", &userInput.time, &userInput.weight, &userInput.drag, velocity);

你实际上是在打印变量的地址:

&userInput.time((userInput.time)的地址)， &userInput.weight((userInput.weight) 的地址), &userInput.drag((userInput.drag) 的地址).

您想打印它们的值，而不是地址，因此在打印时删除“&”:

即；

printf("At t = %f , the parachutist with weight %d kg\nand a drag coefficient %8.2f kg/s \n will have a velocity of %8.2f m/s^2", userInput.time, userInput.weight, userInput.drag, velocity);