将指向结构的指针作为参数传递的优势? [英] advantage of passing pointer to a struct as argument?

问题描述

我们的编码风格是，当我们修改结构的内容时，我们将指向结构的指针传递给函数.

Our coding style is we pass a pointer to a struct to a function, when we are modifying the contents of the structure.

但是，当我们不修改结构体的内容时，还有什么理由更喜欢将指向结构体的指针传递给函数吗?

However, when we are not modifying the contents of a struct, is there still any reason to prefer passing a pointer to a struct to a function?

推荐答案

优点在于传递的大小:当你传递一个大的 struct 时，编译器会生成代码来复制它struct 如果按值传递.这会浪费 CPU 周期，并且可能会导致您的程序耗尽堆栈空间，尤其是在资源稀缺的硬件(例如嵌入式微控制器)上.

The advantage is in the size being passed: when you pass a large struct, the compiler generates code to make a copy of that struct if you pass it by value. This wastes CPU cycles, and may create a situation when your program runs out of stack space, especially on hardware with scarce resources, such as embedded microcontrollers.

当你通过指针传递一个 struct 并且你知道函数不能修改它时，声明指针 const 来强制执行这个规则:

When you pass a struct by pointer, and you know that the function must not make modifications to it, declare the pointer const to enforce this rule:

void take_struct(const struct arg_struct *data) {
    data->field = 123; // Triggers an error
}

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