Static Variables In C Language

In C, the static keyword can be used to create a static variable, which is a variable that retains its value between function calls. A static variable is initialized only once, when the program starts, and its value is preserved until the end of the program.

A static variable is defined by using the static keyword before the variable's data type. Here is an example of how to declare a static variable:

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static int counter = 0;

A static variable can be defined in the global scope or inside a function. When a static variable is defined inside a function, it is only accessible within that function and its value is retained between function calls.

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void func() {    static int num = 0;    num++;    printf("%d", num); }

When the function is called multiple times, the value of the variable "num" will be retained, it will not be reset to 0 as a local variable would.

It's important to note that static variables are only initialized once, when the program starts, and their values are not affected by function calls. This makes them useful for maintaining state information, for example, counting the number of times a function is called or maintaining a running total.

Additionally, when a static variable is defined in the global scope, it's only accessible within the source file in which it's defined and it's not visible to other source files. This makes it useful for creating hidden variables that are only accessible within a specific source file, which can help to encapsulate the implementation details of a program.