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Lambda expressions and function pointers are both mechanisms for encapsulating code in C, but they differ in implementation and characteristics: Implementation method: function pointers point to the memory address of the function, while Lambda expressions are inline anonymous code piece. Return type: The return type of a function pointer is fixed, whereas the return type of a lambda expression is determined by its body code block. Variable capture: Function pointers cannot capture external variables, while lambda expressions can capture external variables by reference or value through the [&] or [=] keywords. Syntax: Use asterisks (*) for function pointers and square brackets ([]) for lambda expressions.
The difference between Lambda expressions and function pointers in C functions
Introduction
Lambda expressions and function pointers are both mechanisms in C for encapsulating code into callable entities. Although they have similar purposes, they have some key differences in their implementation and features.
Implementation
Return type
Variable capture
[&]
(capture by reference) or [=]
(capture by value) keyword external variables. Syntax
returnType (*functionPointerName)(parameterList);
[captureList](parameterList) -> returnType { body }
Practical case
Function pointer case
// someFunction 是一个返回 int 的函数,接受 int 和指针作为参数 int someFunction(int a, int *ptr); // 定义指向 someFunction 的函数指针 int (*pFunc)(int, int *) = someFunction; // 使用函数指针调用 someFunction int result = (*pFunc)(10, &x);
Lambda expression case
// 定义捕获外部变量 x 的 lambda 表达式 auto f = [&](int a) -> int { return a * x; }; // 使用 lambda 表达式 int result = f(10);
Summary of key differences
Features | Function pointer | Lambda expression |
---|---|---|
Implementation | Point to memory address | Inline anonymous code block |
Return type | Fixed to function type | Determined by the body code block |
Variable capture | Prohibited | Allow, capture by value or by reference |
Syntax | Use asterisks (*) | Use square brackets ([]) |
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