C++技巧之五

 

// Original do/while Macro 

//原始的do/while宏

#define MY_ASSERT_ONE(x) do { /

                    if (!(x)) {/

                                       _asm int 3 /

                    } /

                    }  while(0)

// new Macro that removes the loop 

// 新宏移去了loop

#define MY_ASSERT_ONE(x) { /

                    if (!(x)) {  /

                                         _asm int 3  /

                    } /

                    }

 

代码清单 4 避免一个编译器错误

(a). /* This code will cause a compile error */

/* 此段代码将产生一个编译器错误 */

void main(void)

{

                    int i = 10;

                   printf("i: %d/n", i);

                    int j = 100;  /* This statement will cause a compiler error since

                                            it was not declared at the top of the function. */

/* 此语句将导致一个编译器错误，

因为它未在函数顶部声明过。 */

                    printf("j: %d/n", j);

}

(b). /* whereas this code will not */

/*而此段代码将不产生一个编译器错误*/

void main(void)

{

                    int i = 10;

                    printf("i: %d/n", i);

                    {

                                         int j = 100;            /* This statement is fine since it is akin

                                                                                 to defining a local function within the function.  */

/* 此语句很精炼，

因为它在函数中定义了一局部函数的同族。*/

                                         printf("j: %d/n", j);

                    }

}