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# What is an Integer Variable?

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• Written By: Tony Hernandez
• Edited By: O. Wallace
• Last Modified Date: 15 October 2018
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An integer variable is a type of numeric variable in computer programming designed to store a whole number only. This differs from other numeric variable types in that it cannot store decimal values. It is not possible to use integer variables to store values of another data type, such as a string of text or a Boolean variable.

Integer variables are useful if a programmer needs to extract only the whole number from an existing numeral with a decimal value. When a decimal value is anticipated but is either extraneous or undesirable, the value can be placed into an integer variable. This will automatically destroy the decimal portion of the value.

Variables in computer programming work in much the same way that variables work in algebra. Traditional names of algebra variables might be “X” or “Y.” These represent an unknown value that can be determined later by performing calculations. One of the main differences between algebraic and programming variables is that computer programming languages allow the programmer to specify the variable name. This name might be “X,” “Y,” or some other name that gives a clearer indication of what the variable represents.

Computer programming variables all store data of distinct types. These data types determine how the variable can be manipulated. Logical calculations designed for an integer variable cannot be performed on text string or Boolean variables. On the other hand, an integer variable does not allow logical calculations suited to non-numeric variable types.

Many computer programming languages require an integer variable and other variable types to be declared explicitly. This means that the programmer must specify that the variable he or she is declaring is an integer. A programming language might use a specific keyword designed for this purpose. For example, the keyword for declaring an integer variable type in the C++ language is “int.”

In programming languages such as PERL, variables neither have to be declared nor have a type specified in advance of using the variable. The interpreter or compiler determines the variable type according to the operators used on the variable. For example, PERL uses the operator == to determine whether two numeric values store exactly the same information. The operator “eq” determines whether two text string variables contain identical data.

Determining variable types at runtime might cause problems, take up more system resources, and might also slow down the program. This is why most languages require explicit variable declaration.