What is the difference between static variables and dynamic variables in the C language?

The difference between static variables and dynamic variables in the C language is as follows:

1. Storage location: static variables are stored in the static storage area, meaning they exist throughout the entire execution of the program and do not disappear with the function call; dynamic variables are stored in the stack memory, existing only when the function is called and destroyed once the function completes execution.
2. Lifetime: The lifespan of static variables is the same as the program’s execution period, even after a function call ends, the value of static variables remains; on the other hand, the lifespan of dynamic variables is tied to the function call, and after the function call ends, the value of dynamic variables will be destroyed.
3. Default initial values: the default initial value for static local variables and global variables is 0, while dynamic variables have an uncertain initial value and must be initialized manually.
4. Visibility: The scope of static variables is local, but their reach extends to the entire program, meaning other functions in the same source file can also access the static variable; the scope of dynamic variables is also local, but can only be accessed within the function where it is declared.
5. Functionality: Static variables are typically used in cases where data needs to be maintained between function calls, allowing for the recording of the state of the function call; dynamic variables are typically used for data that is only needed temporarily.

To sum up, the lifespan of static variables is related to the program, they have a wide scope and can maintain the status of data; on the other hand, the lifespan of dynamic variables is related to function calls, they have a narrow scope and are commonly used for one-time use data.