How can floating point numbers be compared with 0?

Floating point type variables and 0 We usually take the following way to compare

// First define a macro with a minimum value 
#define ESP 0.00000000000000001

//1. Judge whether it is equal to 0

// Then compare the floating-point number with 0.0 The absolute value of the difference is compared with the minimum 
// If floating-point numbers and 0.0 The absolute value of the difference is less than the minimum , Then we think floating point numbers are equal to 0.0
float a = 0.0f;
scanf("%f",&a);
if(fabs(a - 0.0) < ESP)
{
    
	// that fabs(a - 0.0) == 0
	// namely a - 0.0 The absolute value of is 0
	// namely a = 0.0
}

//2. Judge whether it is greater than 0
if(a >= ESP)
	// that a Greater than 0