Question

我为课写了这个，当你输入这封信时，它应该返回与角色有关的气体。到目前为止，无论有什么人帮忙，我都只能让屏幕返回“未知”。

#include <stdio.h>

int
main(void)
{
char color; /* input- character indicating gass */

// Color of the gas 
printf("Enter first letter of the color of cylinder > ");
scanf_s("%c",&color); /* scan first letter */

/* Display first character followed by gas */
printf("The gas in the cylinder is %c", color);
switch (color) 
{
    case 'O':
    case 'o':
        printf("Ammonia\n");
        break;

    case 'B':
    case 'b':
        printf("Carbon Monoxide\n");
        break;

    case 'Y':
    case 'y':
        printf("Hydrogen\n");
        break;
    case 'G':
    case 'g':
        printf("Oxygen\n");
        break;

    default:
        printf("unknown\n");
} 

return(0);
}

Answer 1

'int'可能是4个字节，而交换机只查看一个字节。因此，开关可能只能看到高位0x00字节的颜色。我尝试的第一件事就是将颜色从int更改为char。

Answer 2

你有什么理由要使用scanf_s（）吗？

这有效：

#include <stdio.h>

int
main(void)
{
int color; /* input- character indicating gass */

// Color of the gas
printf("Enter first letter of the color of cylinder > ");
color=getchar(); /* scan first letter */

/* Display first character followed by gas */
printf("The gas in the cylinder is %c\n", color);
switch (color)
{
    case 'O':
    case 'o':
        printf("Ammonia\n");
        break;

    case 'B':
    case 'b':
        printf("Carbon Monoxide\n");
        break;

    case 'Y':
    case 'y':
        printf("Hydrogen\n");
        break;
    case 'G':
    case 'g':
        printf("Oxygen\n");
        break;

    default:
        printf("unknown\n");
}

return(0);
}

c02kt3esfft0:~ mbobak$ ./test
Enter first letter of the color of cylinder > o
The gas in the cylinder is o
Ammonia
c02kt3esfft0:~ mbobak$ ./test
Enter first letter of the color of cylinder > b
The gas in the cylinder is b
Carbon Monoxide
c02kt3esfft0:~ mbobak$ ./test
Enter first letter of the color of cylinder > y
The gas in the cylinder is y
Hydrogen
c02kt3esfft0:~ mbobak$ ./test
Enter first letter of the color of cylinder > g
The gas in the cylinder is g
Oxygen
c02kt3esfft0:~ mbobak$ ./test
Enter first letter of the color of cylinder > q
The gas in the cylinder is q
unknown

Answer 3

这是因为你正在将一个字符读入未初始化的整数，这将导致未定义的行为。

Answer 4

不是C编码器，但它看起来像你在将字符转换为整数？这就是它无法切换的原因 - 它将char与int进行比较。

Answer 5

您对scanf_s的致电应如下：

char color;
scanf_s("%c",&color,1);

这对我有用。

需要协助在C中使用Switch语句

5 个答案: