What are the application scenarios of actual parameters and formal parameters in the C language?

1. Function call: When a function is called, the actual arguments are passed to the formal parameters for use in the function’s operations.
2. Array passing: When passing an array, the array name is treated as a pointer and passed to the function’s parameter, allowing for manipulation of the array.
3. When passing a structure, the structure variable is passed to the function’s parameter, allowing manipulation of the members within the structure.
4. Dynamic memory allocation: When using dynamic memory allocation, memory size can be passed through actual parameters in order to dynamically allocate memory within the function.
5. Pointer passing: passing a pointer variable as an actual parameter allows the function to change the value of the actual parameter through pointer operations within the function.
6. Callback function: a function pointer can be passed as an argument, allowing the function to be called from within the function.

In conclusion, the applications of actual parameters and formal parameters are very diverse, and they can be used in various situations such as function calls, array passing, structure passing, dynamic memory allocation, pointer passing, and callback functions.