BOOL,float,指针变量与零值比较的if语句

BOOL flag 与“零值”比较的if语句：

标准答案：                                不良风格：

    if(flag)                                       if(flag == TRUE)

    if(!flag)                                      if(flag == 1)

                                                      if(flag == FALSE)

                                                      if(flag == 0)

float  x与“零值”比较的if语句：

标准答案：                                                                错误的写法：

    const float  EPSION = 0.00001                                    if(x = 0.0)

    if((x >= -EPSION) && (x <= EPSION))                        if(x != 0.0)

 

char *p与“零值”比较的if语句：

    标准答案：                                                不良风格：

    if(p == NULL)                                                if(p == 0)

    if(p != NULL)                                                 if(p != 0)

                                                                          if(p)

                                                                          if(!)