[Solved] Evaluating C binary operations

Question

k=25;
++k;
k++;
k|7&12;

After the first 3 lines, k is 27. In the fourth expression, the bitwise AND operator & has higher precedence than the bitwise OR operator |, so it is equivalent to 27|(7&12); Converting the values to binary gives us 11011|(00111&01100); The inner part evaluates to 00100, then 11011|00100 evaluates to 11111, which is 31.

The value of this expression appears in a void context (i.e. it isn’t assigned to anything) and gets discarded.

fp=10/20;

The constants 10 and 20 are both of type int. So integer division is performed, which results in 0. That value is then cast to float and assigned to fp.

fp=(float)10/20;

The constant 10 is casted to float, then divided by 20. Since one of the operands is of type float, the other is promoted to than type and floating point division is performed, resulting in 0.5. That value is then assigned to fp.

Accepted Answer

k=25;
++k;
k++;
k|7&12;

After the first 3 lines, k is 27. In the fourth expression, the bitwise AND operator & has higher precedence than the bitwise OR operator |, so it is equivalent to 27|(7&12); Converting the values to binary gives us 11011|(00111&01100); The inner part evaluates to 00100, then 11011|00100 evaluates to 11111, which is 31.

The value of this expression appears in a void context (i.e. it isn’t assigned to anything) and gets discarded.

fp=10/20;

The constants 10 and 20 are both of type int. So integer division is performed, which results in 0. That value is then cast to float and assigned to fp.

fp=(float)10/20;

The constant 10 is casted to float, then divided by 20. Since one of the operands is of type float, the other is promoted to than type and floating point division is performed, resulting in 0.5. That value is then assigned to fp.