# 使用fallback传递参数

**Published by:** [web3zoom](https://paragraph.com/@web3zoom/)
**Published on:** 2025-07-10
**URL:** https://paragraph.com/@web3zoom/fallback

## Content

巧妙的使用fallback函数传递函数选择器的参数，实现对方法的调用并计算结果。 // SPDX-License-Identifier: GPL-3.0 // 测试 TestFallback -> FallbackInputOutput -> Counter pragma solidity >=0.4.16 <0.9.0; contract FallbackInputOutput{ address immutable target; constructor(address _target){ target = _target; } fallback(bytes calldata data)external payable returns(bytes memory){ (bool success, bytes memory res) = target.call{value: msg.value}(data); require(success,"call failed"); return res; } } contract Counter{ uint256 public count; function inc() external returns(uint256){ count +=1; return count; } } contract TestFallback{ event Log(bytes res); function test(address _fallback, bytes calldata data)external{ (bool ok, bytes memory res) = _fallback.call(data); require(ok,"call failed"); emit Log(res); } function getTestData() external pure returns(bytes memory){ // 函数选择器Counter.inc return abi.encodeCall(Counter.inc,()); } } 知识点： 1、函数选择器的使用 2、fallback的使用 3、abi.encodeCall的使用 另外，不能使用receive方法，因为receive没有返回值

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