Question

我正在尝试编写一个非常简单的程序，将夸脱的水（用户输入）转换为C中的水分子。

#include <stdio.h>
#include <float.h>

int main(void)
{
    float water_quarts;
    float water_grams = (water_quarts*950.00);
    float water_molecules = (water_grams/3e-23F);


    printf("Enter an amount of water in quarts: \n");
    scanf("%f", &water_quarts );
    printf("%f quarts is %f grams of water.\n", water_quarts, water_grams );
    printf("%f grams is %f molecules of water.\n", water_grams, water_molecules );

    return 0;
}

然而，当我编译并运行它时，它给了我：

Enter an amount of water in quarts: 
15
15.000000 quarts is 0.000000 grams of water.
0.000000 grams is 0.000000 molecules of water.

我不完全确定我做错了什么。我在lubuntu 14.10上使用gcc 4.9.1，通过VirtualBox运行。

Answer 1

在您从用户（即water_grams之后）获取water_molecules的输入后，您需要为water_quarts和scanf()分配值。

#include <stdio.h>
#include <float.h>

int main(void)
{
    float water_quarts;
    printf("Enter an amount of water in quarts: \n");
    scanf("%f", &water_quarts );

    float water_grams = (water_quarts*950.00);
    float water_molecules = (water_grams/3e-23F);

    printf("%f quarts is %f grams of water.\n", water_quarts, water_grams );
    printf("%f grams is %f molecules of water.\n", water_grams, water_molecules );

    return 0;
}

或者

float water_quarts;
float water_grams ;
float water_molecules ;


printf("Enter an amount of water in quarts: \n");
scanf("%f", &water_quarts );
water_grams  = (water_quarts*950.00);
water_molecules  = (water_grams/3e-23F);

否则，您正在为它们分配未初始化的值，这就是您获得意外输出的原因。

当你声明一个变量时，它会有一些垃圾值（除非你为它指定一些值），并且由此，当你做

时

float water_grams = (water_quarts*950.00);
float water_molecules = (water_grams/3e-23F);

water_quarts有一些垃圾值，因此，你只是给其他变量分配了一些垃圾。

当float包含等式时，得到0作为结果

1 个答案: