给定3个负数时，如何确保始终打印输入的3个数的中位数（Intro C编程任务）

Question

因此，基本上我的C程序任务是要求/允许用户输入3个整数。 在输入的3个整数中，使用一堆if / else语句，我必须确保它输出3的中位数。

例如，如果用户输入4 5 6，则中位数为5。

我生成的代码可以成功地完成此任务，但当我输入整数-2 -1 -3时除外。 中位数显然是-2，但打印出-1作为中位数。

下面是我的代码；

#include <stdio.h>

int main(int argc, char *argv[]) {
    int firstNumber;
    int secondNumber;
    int thirdNumber;

    printf("Please enter first number: ");
    scanf("%d", &firstNumber);
    printf("PLease enter second number: ");
    scanf("%d", &secondNumber);
    printf("Please enter third number: ");
    scanf("%d", &thirdNumber);

    if (firstNumber < secondNumber && thirdNumber > secondNumber) {
        printf("The median is %d\n", secondNumber);
    } else if (firstNumber < thirdNumber && secondNumber > thirdNumber) {
        printf("The median is %d\n", thirdNumber);
    } else if (firstNumber > secondNumber && firstNumber < thirdNumber) {
        printf("The median is %d\n", firstNumber);
    } else if (firstNumber > thirdNumber && thirdNumber < secondNumber) {
        printf("The median is %d\n", secondNumber);
    } else if (firstNumber > secondNumber && secondNumber < thirdNumber) {
        printf("The median is %d\n", thirdNumber);
    } else if (firstNumber > thirdNumber && secondNumber > firstNumber) {
        printf("The median is %d\n", firstNumber);
    }

    return 0;
}

我已经仔细阅读了每条陈述，但仍然不确定为什么最终的if陈述会给我带来麻烦。

希望有人能帮助我，任何帮助将不胜感激。

Answer 1

此代码非常糟糕。 无论如何，我看到的第一个问题是在线

    } else if (firstNumber > thirdNumber && thirdNumber < secondNumber) {
    printf("The median is %d\n", secondNumber);

if的条件不利于确定secondNumber是中位数。 您仅在检查secondNumber是否大于thirdNumber 。

Answer 2

这是为您提供的解决方案：

median = max(min(a,b), min(max(a,b),c));

---

另外，您需要定义min和max 。

#define max(x, y)    (((x) > (y)) ? (x) : (y))
#define min(x, y)    (((x) < (y)) ? (x) : (y))

Answer 3

您的两个条件错了。 查看修改后的条件（标有注释）：

#include <stdio.h>

int main(int argc, char *argv[]) {
    int firstNumber;
    int secondNumber;
    int thirdNumber;

    printf("Please enter first number: ");
    scanf("%d", &firstNumber);
    printf("PLease enter second number: ");
    scanf("%d", &secondNumber);
    printf("Please enter third number: ");
    scanf("%d", &thirdNumber);

    if (firstNumber < secondNumber && thirdNumber > secondNumber) {
        printf("The median is %d\n", secondNumber);
    } else if (firstNumber < thirdNumber && secondNumber > thirdNumber) {
        printf("The median is %d\n", thirdNumber);
    } else if (firstNumber > secondNumber && firstNumber < thirdNumber) {
        printf("The median is %d\n", firstNumber);
    } else if (firstNumber > thirdNumber && thirdNumber > secondNumber) {  // Changed this line
        printf("The median is %d\n", thirdNumber);        // Changed this line
    } else if (firstNumber > secondNumber && secondNumber > thirdNumber) {  // Changed this line
        printf("The median is %d\n", secondNumber);       // Changed this line
    } else if (firstNumber > thirdNumber && secondNumber > firstNumber) {
        printf("The median is %d\n", firstNumber);
    }

    return 0;
}

注意：如果两个或三个数字相等，则该代码将无效。

Answer 4

尝试以下逻辑-

    if(firstNumber > secondNumber && secondNumber > thirdNumber)
    printf("The Median is %d\n",secondNumber);
    else if(firstNumber < secondNumber && secondNumber < thirdNumber)
    printf("The Median is %d\n",secondNumber);
    else if(firstNumber > secondNumber && firstNumber < thirdNumber)
    printf("The Median is %d\n",firstNumber);
    else if(firstNumber < secondNumber && firstNumber > thirdNumber)
    printf("The Median is %d\n",firstNumber);
    else if(thirdNumber < secondNumber && thirdNumber > firstNumber)
    printf("The Median is %d\n",thirdNumber);
    else if(thirdNumber > secondNumber && thirdNumber < firstNumber)
    printf("The Median is %d\n",thirdNumber);

Answer 5

您输入的数字满足以下条件

} else if (firstNumber > thirdNumber && thirdNumber < secondNumber) {
        printf("The median is %d\n", secondNumber);

实际上，firstNumber和secondNumber都大于thirdNumber。 但是，这种情况并不能确定中位数。 它仅确定两个数字大于第三个数字。

此外，您的代码不考虑某些数字可以彼此相等的情况。

为了避免错误，您应该在表格中写下所有条件

a <= b && b <= c

其中b显然是中位数，并用a，b，c代替变量的组合。

所以代码看起来可能是这样的

#include <stdio.h>

int main(void) 
{
    int firstNumber;
    int secondNumber;
    int thirdNumber;

    printf( "Please enter first number: " );
    scanf( "%d", &firstNumber );
    printf( "PLease enter second number: " );
    scanf( "%d", &secondNumber );
    printf( "Please enter third number: " );
    scanf( "%d", &thirdNumber );

    if ( firstNumber <= secondNumber && secondNumber <= thirdNumber )
    {
        printf( "The median is %d\n", secondNumber );
    }
    else if ( thirdNumber <= secondNumber && secondNumber <= firstNumber )
    {
        printf( "The median is %d\n", secondNumber );
    }
    else if ( thirdNumber <= firstNumber && firstNumber <= secondNumber )
    {
        printf( "The median is %d\n", firstNumber );
    }
    else if ( secondNumber <= firstNumber && firstNumber <= thirdNumber )
    {
        printf( "The median is %d\n", firstNumber );
    }
    else if ( firstNumber <= thirdNumber && thirdNumber <= secondNumber )
    {
        printf( "The median is %d\n", thirdNumber );
    }
    else if ( secondNumber <= thirdNumber && thirdNumber <= firstNumber )
    {
        printf( "The median is %d\n", thirdNumber );
    }

    return 0;
}

如果输入-2 -1 -3，则结果为

The median is -2