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See also: Dynamic (keyword)

In computer programming, a dynamic variable is a variable assigns itself the result of a calculation or operation. The dynamic variable types are dynamic string, dynamic number, and dynamic True/False (Boolean). Dynamic variables calculate their own values by executing commands and logical expressions. Each dynamic variable type allows you to embed an expression. These statements define the value of the variable, potentially based on other variables. The result must match the type of dynamic variable. For example, the code in a dynamic string must evaluate to a string value. Any form of dynamic variable can have an expression embedded in it. These definitions give the variable's value, maybe in light of other variables. The outcome must be consistent with the type of dynamic variable. A dynamic string, for instance, requires that the code evaluate to a string value.

Variable lifetime is contrasted with scope (where a variable can be used): "global" and "local" refer to scope, not lifetime, but scope often implies lifetime. In many languages, global variables are always static, but in some languages they are dynamic, while local variables are generally automatic, but may be static.

In general, dynamic memory allocation is the allocation of memory at run time, unlike static memory allocation where memory is allocated as required at compile time.

Dynamic memory allocation is when an executing program requests that the operating system give it a block of main memory. The program then uses this memory for some purpose. Usually the purpose is to add a node to a data structure.

Example

Dynamic variable names in programming don't have a set name that is hard-coded in the script. They have dynamic names that use string data gleaned from other sources. JavaScript rarely makes use of dynamic variables. But occasionally they are helpful. JavaScript does not have a separate implementation for dynamic variable names as PHP does. But other approaches can also produce outcomes that are comparable. Dynamic variable names in JavaScript can be created, for instance, by utilizing the technique described below.

<script>
	var k = 'value';
	var i = 0;
	for(i = 1; i < 5; i++) {
		eval('var ' + k + i + '= ' + i + ';');
	}
	console.log("value1=" + value1);
	console.log("value2=" + value2);
	console.log("value3=" + value3);
	console.log("value4=" + value4);
</script>

Output:

value1=1
value2=2
value3=3
value4=4

Object-oriented programming

In object-oriented programming, there is also the concept of a static member variable, which is a "class variable" of a statically defined class, i.e., a member variable of a given class which is shared across all instances (objects), and is accessible as a member variable of these objects. A class variable of a dynamically defined class, in languages where classes can be defined at run time, is allocated when the class is defined and is not static.

Object constants known at compile-time, such as string literals, are usually allocated statically. In object-oriented programming, the virtual method tables of classes are usually allocated statically. A statically defined value can also be global in its scope ensuring the same immutable value is used throughout a run for consistency.

See also

• Constant (computer programming)
• Global variable
• Static method
• Thread-local storage

External links

• Dynamic variables by https://learning.postman.com/
• What Is a Dynamic Variable?
• Dynamic script variables
• How to use dynamic variable names in JavaScript ?