5. There are two int variables: a and b, don’t use “if”, “? :”, “switch”orother judgement statements, find out the biggest one of the two numbers.

答案：( ( a + b ) + abs( a - b ) ) / 2　6. 如何打印出当前源文件的文件名以及源文件的当前行号?

答案：

cout << __FILE__ ;

cout<<__LINE__ ;

__FILE__和__LINE__是系统预定义宏，这种宏并不是在某个文件中定义的，而是由编译器定义的。

7. main主函数执行完毕后，是否可能会再执行一段代码，给出说明?

答案：可以，可以用_onexit 注册一个函数，它会在main 之后执行intfn1(void), fn2(void), fn3(void), fn4 (void);

void main( void )

{

String str("zhanglin");

_onexit( fn1 );

_onexit( fn2 );

_onexit(fn3 );

_onexit( fn4 );

printf( "This is executed first.\n" );

}

int fn1()

{

printf( "next.\n" );

return 0;

}

int fn2()

{

printf( "executed " );

return 0;

}

int fn3()

{

printf( "is " );

return 0;

}

int fn4()

{

printf( "This ");

return 0;

}

The _onexit function is passed the address of afunction (func) to be called when the program terminates normally. Successivecalls to _onexit create a register of functions that are executed in LIFO(last-in-first-out) order. The functions passed to _onexit cannot takeparameters.

8. 如何判断一段程序是由C 编译程序还是由C++编译程序编译的?

答案：

#ifdef __cplusplus

cout<<"c++";

#else

cout<<"c";

#endif