C + + code snippet Six

The pros and cons of the Primer Plus floating point:

1 voidtest109 ()2 {3      floatA=2.34e+22f;4      floatb=a+1.0f;5cout<<"A ="<<a<<Endl;6cout<<"b-a="<<b-a<<Endl;7}

Output:
A =2.34e+022
B-a=0================================2.34e+22 is a number that has 23 digits to the left of the decimal point. Add 1, which is the 23rd digit plus 1, but float can only represent the first 6 or the first 7 bits in the number, so modifying the 23rd bit value has no effect.

C + + code snippet Six