请问这是什么意思？

Question

#include<stdio.h>

int main(void)

{

double a;

printf("请输入你的成绩：");

scanf("%lf",a);

switch (a/10) {

case 10:

{

printf("你的成绩是：A");

}

break;

case 9:

{

printf("你的成绩是：B");

}

break;

case 8:

{

printf("你的成绩是：C");

}

break;

case 7:

{

printf("你的成绩是：D");

}

break;

case 6:

{

printf("你的成绩是：E");

}

break;

default:

{printf("请重新输入：");

}

}

}

C:\Program Files (x86)\Microsoft Visual Studio\Common\MSDev98\Bin\7.c(7) : error C2050: switch expression not integral

Error executing cl.exe.

Answer 1

应该是是已经有个cl.exe执行，还没退出，再要编译执行，就会出现这样。解决方法：1. 打开vc界面，点击VC“TOOLS（工具）”；2. 然后点击“Option（选择）” ；3. 点击“Directories（目录）”；4. 重新设置“Excutable Fils、Include Files、 Library Files、Source Files”的路径。如果你是按照初始路径安装vc6.0的，路径应为：executatble files:C:\Program Files\Microsoft Visual Studio\Common\MSDev98\Bin    C:\Program Files\Microsoft Visual Studio\VC98\BINC:\Program Files\Microsoft Visual Studio\Common\TOOLSC:\Program Files\Microsoft Visual Studio\Common\TOOLS\WINNTinclude files:C:\Program Files\Microsoft Visual Studio\VC98\INCLUDEC:\Program Files\Microsoft Visual Studio\VC98\MFC\INCLUDEC:\Program Files\Microsoft Visual Studio\VC98\ATL\INCLUDElibrary files:C:\Program Files\Microsoft Visual Studio\VC98\LIBC:\Program Files\Microsoft Visual Studio\VC98\MFC\LIBsource files:C:\Program Files\Microsoft Visual Studio\VC98\MFC\SRCC:\Program Files\Microsoft Visual Studio\VC98\MFC\INCLUDEC:\Program Files\Microsoft Visual Studio\VC98\ATL\INCLUDEC:\Program Files\Microsoft Visual Studio\VC98\CRT\SRC