Zhou Ligong teaches you to learn C language programming and programming: this is best to write a function pointer array.

The second chapter focuses on programming technology. In this section, we’ll discuss function pointer arrays, specifically under subsection 2.1.4. Function pointer arrays are essentially arrays where each element holds the address of a function, enabling dynamic execution based on certain conditions.

Imagine you’re building a simple pocket calculator. After reading two numbers, op1 and op2, along with an operator, oper, you could use a series of if-else or switch-case statements to determine which operation to perform. For instance:

However, if your calculator supports hundreds of operations, such a switch-case structure would become cumbersome and difficult to manage. A more efficient approach is to utilize a transfer table, which is essentially an array of function pointers. Each element in this array points to a specific function. Consider the following example:

In this case, PF represents a pointer type to a function that returns a double and takes two double parameters. To store the addresses of four functions, you could declare an array variable named `oper_func` using PF:

Though the syntax may differ slightly, the meaning remains consistent. Assigning values to elements in a function pointer array is similar to assigning values to regular array elements. For instance:

To build a transfer table, you must declare and initialize an array of function pointers. Ensure that the function prototypes are declared before the array definition. Here’s an example:

This statement initializes four elements, eliminating the need for subsequent assignments. It’s crucial to ensure that the order of function names in the initialization list aligns with the integer codes used to represent each operator in your program. In this example, ADD, SUB, MUL, and DIV correspond to 0, 1, 2, and 3, respectively. The call format looks like this:

Here, the `oper` variable selects the appropriate function pointer from the array, and the function call operator executes the selected function. Alternatively, you can omit the size of the array and let the initialization list determine its size:

The initial values in the braces dictate the number of elements in the array, making the initialization list for a function pointer array identical to that of other arrays.

For additional resources, readers can reply to the keyword "[programming]" in our public account to access two books: “Programming for AMetal Framework and Interface (Top)” and “Programming and Data Structures.”

The book "Programming for AMetal Frameworks and Interfaces (I)" is currently in the printing phase and will be announced upon release. The Taobao purchase link for "Programming and Data Structures" is as follows, which can be copied into a browser to open:

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For further reading, here are some relevant topics:

Zhou Ligong: A Callback Function That Must Be Mastered in Software Module Layered Design

Zhou Ligong: Dynamically Distributed Memory – free() Function and realloc() Function

Zhou Ligong: Dynamically Distributed Memory – malloc() Function and calloc() Function

Zhou Ligong: Constructing a Double Pointer with an Array

Zhou Ligong: Do You Know That Arrays Can Also Save Pointers?

Zhou Ligong: The True Value of Characters Lies in the Formation of Character Sequences – String Functions

Zhou Ligong: The True Value of Characters Lies in the Formation of Character Sequences – Input and Output of Strings

Zhou Ligong: The True Value of Characters Lies in the Formation of Character Sequences – Reference to a String

Zhou Ligong: Characters Can Be Calculated Like Integers

Zhou Ligong: How to Pass a Two-Dimensional Array as a Function Parameter

Zhou Ligong: Generalization of Algorithms, You Should Know

Zhou Ligong: Generic Programming – Implementing Code Reuse

Zhou Ligong: Four Methods and Idioms for Array Access

Zhou Ligong: The Rules of the Array, Do You Know?

Zhou Ligong: C Language Array and Pointer Detailed Explanation

Zhou Ligong: Implementing and Using an Easy-to-Use Abstract Interface

Zhou Ligong: Five Things to Pay Attention to When Designing a Good Program Interface

Zhou Ligong: New Thinking and New Methods of Programming

Zhou Ligong: Splitting Conditional Statements Makes Code Easier to Understand – Comprehensive Expressions and Conditional Expressions

Zhou Ligong: Splitting Conditional Statements Makes Code Easier to Understand – Logical Expressions

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