An answer to the C function pointer

The biggest use of a function pointer is that it can be called by a template method, which I learned when learning the Java design pattern. for example, two functions have the same process structure, but the specific functions called internally are different, as shown in the following figure: void func1 () {// a process Code And Aspect-Oriented proxy, such as security check and logging int sum = add (x, y); // a piece of Process Code and Aspect-Oriented proxy, such as security check, log Record, etc.} void func2 () {// a piece of Process Code exactly the same as func1 and an aspect-oriented proxy, such as int Difference = sub (X, y); // a piece of Process Code exactly the same as func1 and an aspect-oriented proxy, such as security check and logging}. Then, you can define only one function, void func (pfunc p) {// Process Code and Aspect-Oriented proxy exactly the same as func1, such as int Difference = p (x, y); // a piece of Process Code exactly the same as func1 and an aspect-oriented proxy, such as security check and logging} call Program During the call, let the parameter P point to the ADD and sub functions, respectively. For other questions, since the focus of my writing and work is no longer at all C Language I have no time to answer questions one by one. I will use the answers released by jackie214 to respond to you.