Conversions

ints and doubles are different types. Computers can

• do double arithmetic
• do int arithmetic

They can't do mixed arithmetic. Instead, they convert from one type to the other.

In the example evaluation of the term 2 * x requires an implicit conversion.

The 2 is automatically converted to a double yielding 2.0 * x and then a double multiply is called.

 

Exercises

What will the following functions return (and what conversions will be carried out inside them)?

1. int fee() {
     return (11/6+11%6);
   }

2. int fi() {
     return (1.1 + 10.0/5);
   }

3. double fo() {
     return (3 * 6 – 12.0 / 5 + 4);
   }

No conversions—all operations are integer. 11/6 = 1 & 11%6 = 5 so 6 is returned.

5 is converted to 5.0,       10.0/5.0 = 2.0    1.1 + 2.0 = 3.1    converted to int for return so 3 is returned.

5 is converted to 5.0,       12.0/5.0 = 2.4    3 * 6 = 18     18 and 4 are converted to double—18.0 and 4.0—for summation with 2.4 yielding 19.6 which is the double returned.