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This article mainly introduces how to use the Static keyword in C language. It is very detailed and has a certain reference value. Friends who are interested must finish reading it.

I. the basic meaning of the static keyword

First of all, the static keyword means static and is used to modify local variables, global variables and functions, and modify their data storage types.

1. Local variable: a variable defined inside any function (without static). If the initial value is uncertain, the output function is automatically destroyed and stored in the stack area. When you modify this variable with static, the compiler initializes it to zero and stores it in the static zone. When the function returns, the value remains the same, the output function is not destroyed, and the next entry function still exists. Root cause-static-decorated local variables are stored in the static zone.

two。 Global variable: the ordinary global variable is defined outside the function body, the storage space is allocated in the static zone, and the compiler initializes it automatically. Ordinary global variables are visible to the entire project, and other files can be used directly after being declared externally using the keyword extern. Static global variables are only visible to the current file, other files are not accessible, and other files can define variables with the same name, which do not affect each other. When defining global variables that do not need to be shared with other files, adding the static keyword can effectively reduce the coupling between program modules, avoid conflicts of variables with the same name in different files, and will not be misused.

3. Function: add static to the return type of the function, which is a static function. For example, the static int main () static function is visible only in the file in which it is declared, and cannot be referenced by other files. Different files can use the same name static function non-static function can be referenced directly in another file.

II. The usage of the static keyword

1. When using ordinary local variables, as shown in the figure, int an is a local variable, which is automatically destroyed after each function, so "6666666666" is printed out.

When using static local variables, as shown in the figure. Static-modified local variables will not be destroyed except for the local scope, and the next entry function will still exist.

two。 As shown in the figure, the function of static name cannot be referenced by another file.

Third, the principle of static keyword

Because the local variables decorated by static are stored in the static area, when static modifies the global variables, it actually changes where the variables are stored. Local variables are placed in the stack area, modified by static and placed in the static area. As a result, the life cycle does not end except that the scope still exists.

The picture shows a schematic diagram of the storage area.

The above is all the content of this article entitled "how to use Static keywords in C language". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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