The difference between C++ inline functions and function pointers

Inline functions are directly expanded without calling, while function pointers store variables pointing to function addresses, allowing indirect function calls.

C The difference between inline functions and function pointers

What is an inline function?

Inline functions are functions that the compiler expands directly at compile time. This means that a call to an inline function does not result in an actual function call, but rather the function code is inserted directly into the location where it is called.

Syntax:

inline 返回值类型 函数名(参数列表) {
    // 函数体
}

Advantages:

##Avoid the overhead of function calls and improve performance.
• The code is more concise and easier to read.

What is a function pointer?

A function pointer is a variable that stores the address of a function. It allows us to call functions in an indirect way.

Syntax:

类型 (*函数名)(参数列表);

The type represents the return value type of the function pointer, and the parameter list represents the formal parameter type of the function pointer.

Advantages:

Provides flexibility in function calls.
• Allows us to change functions at runtime.

Practical case

Inline function:

Consider the following for calculating Fibonacci numbers Inline functions:

inline int fibonacci(int n) {
    if (n == 0) {
        return 0;
    } else if (n == 1) {
        return 1;
    } else {
        return fibonacci(n - 1) + fibonacci(n - 2);
    }
}

Function pointers:

Consider the following code that uses function pointers to calculate Fibonacci numbers:

int (*fib_ptr)(int);

int fibonacci_using_ptr(int n) {
    if (n == 0) {
        return 0;
    } else if (n == 1) {
        return 1;
    } else {
        return fib_ptr(n - 1) + fib_ptr(n - 2);
    }
}

int main() {
    fib_ptr = fibonacci;
    cout << fibonacci_using_ptr(10) << endl; // 输出：55
    return 0;
}

In this example , the function pointer

fib_ptr is assigned to the inline function fibonacci, which is then used to call the function indirectly.

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