Compare with other programming language, string comparison cannot be done with == or != in Solidity. It is because Solidity do not support operator natively. To doing so, it needs workaround.
We need to hash string to byte array to compare value in Solidity. Sample code as below.
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| // SPDX-License-Identifier: GPL-3.0 | |
| pragma solidity >=0.7.1 <0.9.0; | |
| contract IsEqualStringContract { | |
| function equals(string memory a, string memory b) public pure returns (bool) { | |
| if(bytes(a).length != bytes(b).length) { | |
| return false; | |
| } else { | |
| return keccak256(abi.encodePacked(a)) == keccak256(abi.encodePacked(b)); | |
| } | |
| } | |
| } |
When execute, result as below.
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