Difference between revisions of "Increment and Decrement Operators"
m (added minor section on +=, *=, etc.) |
(removed stuff like x = x++. who does that?) |
||
Line 35: | Line 35: | ||
Note that the regular [[Your_First_Java_Program#Rules_for_Evaluating_Expressions|rules for arithmetic]] in Java apply here. Be careful not to unintentionally increment or decrement beyond the range a variable can hold. Strange things can happen when this occurs. | Note that the regular [[Your_First_Java_Program#Rules_for_Evaluating_Expressions|rules for arithmetic]] in Java apply here. Be careful not to unintentionally increment or decrement beyond the range a variable can hold. Strange things can happen when this occurs. | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
== Combined Assignment Operators == | == Combined Assignment Operators == | ||
Line 89: | Line 67: | ||
The increment and decrement operators are used to add or subtract one from a variable. These operators can be used on the basic data types of int, long, float, and double. The operators can be used as part of a complex expression or as a simple expression. The most common use for the increment operator is as a counter. The increment and decrement operators easily add or subtract one to a variable. | The increment and decrement operators are used to add or subtract one from a variable. These operators can be used on the basic data types of int, long, float, and double. The operators can be used as part of a complex expression or as a simple expression. The most common use for the increment operator is as a counter. The increment and decrement operators easily add or subtract one to a variable. | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− |
Revision as of 15:13, 10 October 2008
COMP 1010 Home > Java Fundamentals
IntroductionIncrement and decrement are arithmetic operators which quickly add or subtract one from a variable. These operators work on basic data types such as int and long. These operators can appear as an expression by themselves or as part of a complex expression. Increment and decrement can be used to add or subtract one from a variable.
|
---|
{{{Body}}}
The Increment and Decrement Operators
The increment and decrement operators increase or decrease the value of a variable by 1. The increment operator is ++
and decrement is --
. These operators can be used on int, long, float and double data types. They are primarily used on integer value variables such as int and long. Increasing or decreasing the value of a variable can be done by using the increment or decrement operators.
Usage
There are two ways to use these operators. We can use these operators on their own along with a variable, or as part of a larger expression. Using them as part of a larger expression may be difficult depending on the complexity of the expression. As useful as these operators are, we should always keep in mind that code readability is important. Care should be taken when using these operators in complex expressions. We look at the two ways of using increment and decrement below.
Basic Expression
We can use these operators by placing them before or after the variable. If the operator is placed before a variable, it is known as preincrement or predecrement. Pre - increment/decrement means the variable is increased or decreased before we use it for anything else. If the operator is placed after a variable, it is known as postincrement or postdecrement. Post - increment/decrement means the variable is used by the expression and then modified after.
The following code snippet demonstrates the difference between these four operators:
int number = 5; ++number; // preincrement, the variable 'number' would be 6 as a result number++; // postincrement, the variable 'number' would be 7 as a result --number; // predecrement, number = 6 number--; // postdecrement, number = 5
When an expression is only the increment or decrement operator, there is no difference between post and pre. The results are the same. You can change ++number with number++ and still get the same results.
These increment and decrement expressions are really shorthand for:
number = number + 1; // longer way of writing number++ or ++number number = number - 1; // longer way of writing number-- or --number
Note that the regular rules for arithmetic in Java apply here. Be careful not to unintentionally increment or decrement beyond the range a variable can hold. Strange things can happen when this occurs.
Combined Assignment Operators
Often, you will not want to increase or decrease a variable by one, but by a different value which may be a constant (like 2) or stored in a variable. Fortunately, there are combined assignment operators which are shorthand for these types of statements:
|
Summary
The increment and decrement operators are used to add or subtract one from a variable. These operators can be used on the basic data types of int, long, float, and double. The operators can be used as part of a complex expression or as a simple expression. The most common use for the increment operator is as a counter. The increment and decrement operators easily add or subtract one to a variable.