Compare different data types with zero values.

1. bool type: bool type variables cannot be directly compared with TRUE, FALSE, or 1 or 0.

In the bool type, the non-zero value is TRUE, and the zero value is FALSE ). There is no definite value for TRUE. The value of VC ++ is 1, and the value of VB is-1.

The correct comparison method is:

Bool flag = 1;

If flag ){}

If! Flag ){}

2. int type: int type variables are directly compared with 0.

Int a = 1;

If a = 0 ){}

If! = 0 ){}

3. float variable: Do not use "=" or "! = "To compare with any number, we should try to convert it to the form of"> = "and" <=.

Float a = 3/5;

If a >=- value) & (a <= value) {}// value is the allowed precision

4. pointer: Compare pointer variables with NULL.

Because the NULL value of the pointer variable is NULL ):

Int;

Int * p =;

If p = NULL ){}