宏定义#井号的用法

单个井号（#）：在宏展开的时候会将#后面的参数替换成相应的字符串

#include <stdio.h> #define Printi(message) printf(#message " = %d\n", message) #define Printd(message) printf(#message " = %lf\n", message) #define Prints(message) printf(#message " = %s\n", message) int main(int argc, char *argv[]) { int i_ = 10; double d_ = 5.0; char c[] = "hello"; Printi(i_); Printd(d_); Prints(c); return 0; }

两个井号（##）：起连接符的作用，将前后两个参数连接为一个子串，但连接后的子串不能当成字符串形式

#include <stdio.h> #define Print(n) printf("token" #n " = %d\n", token##n) int main(int argc, char *argv[]) { int token1 = 10; Print(1); return 0; }

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《C++ 编程思想》P95页

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#include <iostream> using namespace std; #define P(message) cout<< #message<<" = "<<message<<endl; int main(int argc, char *argv[]) {     int i_ = 10;     double d_ = 5.0;     string s_ = "hello";     P(i_);     P(d_);     P(s_);     return 0; }

另可以参考：http://blog.csdn.net/morewindows/article/details/6697488