Programming in C

444 Appendix A C Language Summary

a - b subtracts bfrom a;

a * b multiplies aby b;

a / b divides aby b;

i % j gives the remainder of idivided by j.

In each expression, the usual arithmetic conversions are performed on the operands (see

Section 5.17). If ais unsigned,–ais calculated by first applying integral promotion to it,

subtracting it from the largest value of the promoted type, and adding 1 to the result.

If two integral values are divided, the result is truncated. If either operand is negative,

the direction of the truncation is not defined (that is, –3 / 2 might produce –1 on some

machines and –2 on others); otherwise, truncation is always toward zero (3 / 2 always

produces 1). See Section 5.15 for a summary of arithmetic operations with pointers.

5.4 Logical Operators

Given that

a, b are expressions of any basic data type except void, or are both

pointers;

then the expression

a && b has the value 1 if both aand bare nonzero, and 0 otherwise (and bis

evaluated only if ais nonzero);

a || b has the value 1 if either aor bis nonzero, and 0 otherwise (and bis

evaluated only if ais zero);

! a has the value 1 if ais zero, and 0 otherwise.

The usual arithmetic conversions are applied to aand b(see Section 5.17).The type of

the result in all cases is int.

5.5 Relational Operators

Given that

a, b are expressions of any basic data type except void, or are both

pointers;

then the expression

a < b has the value 1 if ais less than b,and 0 otherwise;

a <= b has the value 1 if ais less than or equal to b,and 0 otherwise;

a > b has the value 1 if ais greater than b,and 0 otherwise;

a >= b has the value 1 if ais greater than or equal to b, and 0 otherwise;

a == b has the value 1 if ais equal to b,and 0 otherwise;

a != b has the value 1 if ais not equal to b,and 0 otherwise.

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