Programming in C

5.0 Expressions 445

The usual arithmetic conversions are performed on aand b(see Section 5.17).The first

four relational tests are only meaningful for pointers if they both point into the same

array or to members of the same structure or union.The type of the result in each case

is int.

5.6 Bitwise Operators

Given that

i, j, n are expressions of any integer data type;

then the expression

i & j performs a bitwise AND of iand j;

i | j performs a bitwise OR of iand j;

i ^ j performs a bitwise XOR of iand j;

~i takes the ones complement of i;

i << n shifts ito the left nbits;

i >> n shifts ito the right nbits.

The usual arithmetic conversions are performed on the operands, except with <<and >>,

in which case just integral promotion is performed on each operand (see Section 5.17).

If the shift count is negative or is greater than or equal to the number of bits contained

in the object being shifted, the result of the shift is undefined. On some machines, a

right shift is arithmetic (sign fill) and on others logical (zero fill).The type of the result

of a shift operation is that of the promoted left operand.

5.7 Increment and Decrement Operators

Given that

lv is a modifiable lvalueexpression, whose type is not qualified as

const;

then the expression

++lv increments lvand then uses its value as the value of the expression;

lv++ uses lvas the value of the expression and then increments lv;

--lv decrements lvand then uses its value as the value of the expression;

lv-- uses lvas the value of the expression and then decrements lv.

Section 5.15 describes these operations on pointers.

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