“记忆”有什么区别。并“存储”关键词

发布于 2025-02-11 19:05:28 字数 501 浏览 0 评论 0原文

pragma solidity >=0.5.0 <0.6.0;

contract ZombieFactory {

    uint dnaDigits = 16;
    uint dnaModulus = 10 ** dnaDigits;

    struct Zombie {
        string name;
        uint dna;
    }

    Zombie[] public zombies;

    function createZombie (string memory _name, uint _dna) public {
        // start here
    }

}

在这里，我感到困惑，因为根据这篇文章

= 743A8DDB20C449DF924652051C14EF26 函数参数始终在内存中“ ”。因此，这是否意味着在此代码中，当我们将字符串_name作为函数参数传递时，它将被分配给内存，还是像所有其他状态变量一样保留在存储中？

原文

pragma solidity >=0.5.0 <0.6.0;

contract ZombieFactory {

    uint dnaDigits = 16;
    uint dnaModulus = 10 ** dnaDigits;

    struct Zombie {
        string name;
        uint dna;
    }

    Zombie[] public zombies;

    function createZombie (string memory _name, uint _dna) public {
        // start here
    }

}

Here I am confused because as per this post https://ethereum.stackexchange.com/questions/1701/what-does-the-keyword-memory-do-exactly?newreg=743a8ddb20c449df924652051c14ef26

"the local variables of struct are by-default in storage, but the function arguments are always in memory".
So does it mean that in this code when we pass string _name as a function argument, it will be assigned to memory or will it remain in the storage like all other state variables?

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雨后咖啡店 2025-02-18 19:05:28

所有状态变量均已永久存储在存储中。就像硬盘存储一样。

记忆就像RAM。当合同完成其代码执行时，将清除内存。

有时，在声明状态变量后，您需要在功能中修改它。例如，您定义了

 Zombie[] public zombies;

function createZombie (string memory _name, uint _dna) public {
        Zombie storage firstZombie=zombies[0]
        // mutate the name of the firstZombie
        firstZombie.name=_name
        // you have actually mutated state variable zonbies
    }

如果使用内存关键字，则实际上将将值复制到内存：

function createZombie (string memory _name, uint _dna) public {
            // firstZombie is copied to the memory
            // New memory is allocated.
            Zombie memory firstZombie=zombies[0]
            // mutate the name of the firstZombie
            firstZombie.name=_name
            return firstZombie
            // this did not mutate the state variable zombies
            // after returning allocated memory is cleared
        }

以固体性，函数参数变量存储在内存中。

All the state variables are stored in storage permanently. It is like hard disk storage.

Memory is like RAM. When a contract finishes its code execution, the memory is cleared.

Sometimes after you declared a state variable, you want to modify it inside a function. For example you defined

 Zombie[] public zombies;

function createZombie (string memory _name, uint _dna) public {
        Zombie storage firstZombie=zombies[0]
        // mutate the name of the firstZombie
        firstZombie.name=_name
        // you have actually mutated state variable zonbies
    }

If you used memory keyword, you would be actually copying the value to the memory:

function createZombie (string memory _name, uint _dna) public {
            // firstZombie is copied to the memory
            // New memory is allocated.
            Zombie memory firstZombie=zombies[0]
            // mutate the name of the firstZombie
            firstZombie.name=_name
            return firstZombie
            // this did not mutate the state variable zombies
            // after returning allocated memory is cleared
        }