数字‘e'的输入
作为数字的"e"，输入后，编译出现错误：第一次出现"e”没有定义“e",怎么办？
[解决办法]
double e = 2.718281828;
[解决办法]
是数学上log运算的e吗?如果是,引用math.h里面的宏,如下:
#define M_E 2.7182818284590452354 /* e */
或者自己定义.
[解决办法]
# define M_El2.7182818284590452353602874713526625L /* e */
[解决办法]

File: "c:\Microsoft SDK\src\crt\math.h" 2 occurrences found on 2 lines
   141:  * M_E        - e
   156: #define M_E        2.71828182845904523536
File: "C:\Program Files\Microsoft Visual Studio 8\VC\include\math.h" 2 occurrences found on 2 lines
   606:  * M_E        - e
   621: #define M_E        2.71828182845904523536
File: "C:\Program Files\Microsoft Visual Studio 9.0\VC\include\math.h" 2 occurrences found on 2 lines
   606:  * M_E        - e
   621: #define M_E        2.71828182845904523536
File: "C:\Program Files\Microsoft Visual Studio 10.0\VC\include\math.h" 2 occurrences found on 2 lines
   612:  * M_E        - e
   627: #define M_E        2.71828182845904523536