Previous Section
1.4 References		 | Table of Contents | Index | Next Section
1.6 Statements

1.5.1 Postfix

 

Postfix operators are operators that are suffixed to an expression.
operand++;
This causes the value of the operand to be returned. After the result is obtained, the value of the operand is incremented by 1.
operand--;
This is the same but the value of the operand is decremented by 1.

 

Examples:
int joe=3;
joe++;
The value of joe is now 4.
printf("%i",joe++);
This outputs the number 4. The value of joe is now 5.

1.5.2 Unary and Prefix

 

Prefix operators are operators that are prefixed to an expression.
++operand;
This causes the value of the operand to be incremented by 1. Its new value is then returned.
--operand;
This is the same but the value of the operand is decremented by 1.
!operand
Returns the logical NOT operation on the operand. A true operand returns false, a false operand returns true. Also known as the bang operand.
~operand
Returns the compliment of the operand. The returned value is the operand with its bits reversed (1's become 0's, 0's become 1's).

 

Examples:
int bart=7;
printf("%i",--bart);
This outputs the number 6. The value of bart is now 6.

int lisa=1;
printf("%i",!lisa);
This outputs 0 (false).

1.5.3 Normal

 

There are several normal operators which return the result defined for each:
expression1 + expression
The result of this is the sum of the two expressions.

expression1 - expression2
The result of this is the value of expression2 subtracted from expression1.

expression1 * expression2
The result of this is the value of expression1 multiplied by expression2.

expression1 / expression2
The result of this is the value of expression1 divided by expression2.

expression1 % expression2
The result of this is the value of the remainder after dividing expression1 by expression2. Also called the modulo operator.

expression1 & expression2
Returns a bitwise AND operation done on expression1 and expression2. The result is a value the same size as the expressions with its bits modified using the following rules: Both bits must be 1 (on) to result in 1 (on), otherwise the result is 0 (off).
e1 e2 Result
0 0 0
0 1 0
1 0 0
1 1 1

expression1 | expression2
Returns a bitwise OR operation done on expression1 and expression2. The result is a value the same size as the expressions with its bits modified using the following rules: Both bits must be 0 (off) to result in 0 (off), otherwise the result is 1 (on).
e1 e2 Result
0 0 0
0 1 1
1 0 1
1 1 1

expression1 ^ expression2
Returns a bitwise XOR operation done on expression1 and expression2. The result is a value the same size as the expressions with its bits modified using the following rules: If both bits are the same, then the result is 0 (off), otherwise the result is 1 (on).
e1 e2 Result
0 0 0
0 1 1
1 0 1
1 1 0

expression1 >> shift_value
Returns expression1 with its bits shifted to the right by the shift_value. The leftmost bits are replaced with zeros if the value is nonnegative or unsigned. This result is the integer part of expression1 divided by 2 raised to the power of shift_value. If expression1 is signed, then the result is implementation specific.

expression1 << shift_value
Returns expression1 with its bits shifted to the left by the shift_value. The rightmost bits are replaced with zeros. This result is the value of expression1 multiplied by the value of 2 raised to the power of shift_value. If expression1 is signed, then the result is implementation specific.

1.5.4 Boolean

 

The boolean operators return either 1 (true) or 0 (false).
expression1 && expression2
Returns the logical AND operation of expression1 and expression2. The result is 1 (true) if both expressions are true, otherwise the result is 0 (false).
e1 e2 Result
0 0 0
0 1 0
1 0 0
1 1 1

expression1 || expression2
Returns the logical OR operation of expression1 and expression2. The result is 0 (false) if bother expressions are false, otherwise the result is 1 (true).
e1 e2 Result
0 0 0
0 1 1
1 0 1
1 1 1

expression1 < expression2
Returns 1 (true) if expression1 is less than expression2, otherwise the result is 0 (false).

expression1 > expression2
Returns 1 (true) if expression1 is greater than expression2, otherwise the result is 0 (false).

expression1 <= expression2
Returns 1 (true) if expression1 is less than or equal to expression2, otherwise the result is 0 (false).

expression1 >= expression2
Returns 1 (true) if expression1 is greater than or equal to expression2, otherwise the result is 0 (false).

expression1 == expression2
Returns 1 (true) if expression1 is equal to expression2, otherwise the result is 0 (false).

expression1 != expression2
Returns 1 (true) if expression1 is not equal to expression2, otherwise the result is 0 (false).

1.5.5 Assignment

 

An assignment operator stores the value of the right expression into the left expression.
expression1 = expression2
The value of expression2 is stored in expression1.

expression1 *= expression2
The value of expression1 times expression2 is stored in expression1.

expression1 /= expression2
The value of expression1 divided by expression2 is stored in expression1.

expression1 %= expression2
The value of the remainder of expression1 divided by expression2 is stored in expression1.

expression1 += expression2
The value of expression1 plus expression2 is stored in expression1.

expression1 -= expression2
The value of expression1 minus expression2 is stored in expression1.

expression1 <<= shift_value
The value of expression1's bits are shifted to the left by shift_value and stored in expression1.

expression1 >>= shift_value
The value of expression1's bits are shifted to the right by shift_value and stored in expression1.

expression1 &= expression2
The value of the bitwise AND of expression1 and expression2 is stored in expression1.
e1 e2 Result
0 0 0
0 1 0
1 0 0
1 1 1

expression1 ^= expression2
The value of the bitwise XOR of expression1 and expression2 is stored in expression1.
e1 e2 Result
0 0 0
0 1 1
1 0 1
1 1 0

expression1 |= expression2
The value of the bitwise OR of expression1 and expression2 is stored in expression1.
e1 e2 Result
0 0 0
0 1 1
1 0 1
1 1 1

1.5.6 Precedence

 

The operators have a set order of precedence during evaluation. Items encapsulated in parenthesis are evaluated first and have the highest precedence. The following chart shows the order of precedence with the items at the top having highest precedence.

 

Operator Name
! Logical NOT. Bang.
++ -- Increment and decrement operators.
* / % Multiplicative operators.
+ - Additive operators.
<< >> Shift operators.
< > <= >= Inequality comparators.
== != Equality comparators
& Bitwise AND.
^ Bitwise XOR.
| Bitwise OR.
&& Logical AND.
|| Logical OR.
?: Conditional.
= op= Assignment.

 

Examples:
17 * 5 + !(1+1) && 0
Evaluates to 0 (false).
5+7<4
Evaluates to 1 (true).
a<b<c
Same as (a<b)<c.
Previous Section
1.4 References		 | Table of Contents | Index | Next Section
1.6 Statements