# 【Import】

如果我們要從 local 的方式 import 檔案，可以假設 Folder Structure 如下：

```
├── Import.sol
└── Foo.sol
```

創建一個名為 `Foo.sol` 的檔案：

```solidity
pragma solidity ^0.8.11;

struct Point {
    uint x;
    uint y;
}

error Unauthorized(address caller);

function add(uint x, uint y) pure returns (uint) {
    return x + y;
}

contract Foo {
    string public name = "Foo";
}
```

接下來創建一個名為 `Import.sol` 的檔案，並且在裡面 import `Foo.sol`：

```solidity
pragma solidity ^0.8.10;

// import Foo.sol from current directory
import "./Foo.sol";

// import {symbol1 as alias, symbol2} from "filename";
import {Unauthorized, add as func, Point} from "./Foo.sol";

contract Import {
    // Initialize Foo.sol
    Foo public foo = new Foo();

    // Test Foo.sol by getting it's name.
    function getFooName() public view returns (string memory) {
        return foo.name();
    }
}
```

當然也可以繼承其他地方來的合約：

```solidity
import "./someothercontract.sol";

contract newContract is SomeOtherContract {

}
```

如果要從 External 的地方像是 GitHub import 可以藉由複製 url 方式 import：

```solidity
// https://github.com/owner/repo/blob/branch/path/to/Contract.sol
import "https://github.com/owner/repo/blob/branch/path/to/Contract.sol";

// Example import ECDSA.sol from openzeppelin-contract repo, release-v3.3 branch
// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/cryptography/ECDSA.sol
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.3/contracts/cryptography/ECDSA.sol";
```


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