Resolving Identifier Not Found Error in Solidity ERC20 Contract

Описание: Discover how to solve the common "Identifier not found" error in your Solidity ERC20 contract with our detailed guide.
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This video is based on the question https://stackoverflow.com/q/68785206/ asked by the user 'Wayneio' ( https://stackoverflow.com/u/1240649/ ) and on the answer https://stackoverflow.com/a/68786129/ provided by the user 'Petr Hejda' ( https://stackoverflow.com/u/1693192/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the "Identifier Not Found" Error in Solidity ERC20 Contracts

When developing smart contracts with Solidity, especially ERC20 tokens, encountering errors can be frustrating. One particularly common error is the "Identifier not found or not unique." If you've come across this error while trying to compile your contract, you're not alone. In this guide, we will dive into the causes of this error and how to fix it so you can continue on your path to building your Ethereum-based applications.

The Error Breakdown

Imagine you are creating an ERC20 token called ACoolToken. You might run into an error message like this when trying to compile your Solidity code:

[[See Video to Reveal this Text or Code Snippet]]

This indicates that the Solidity compiler has encountered a problem with how identifiers are declared or named in your code. In this specific case, the issue arises from a simple typo in the function definition.

Diagnosing the Problem

Looking closely at the code snippet you provided, the error stems from the following line:

[[See Video to Reveal this Text or Code Snippet]]

The identification of unint is incorrect. It should be uint, which stands for unsigned integer.

Correcting the Typo

To resolve this, update the unint keyword to uint like so:

[[See Video to Reveal this Text or Code Snippet]]

This change will eliminate the "Identifier not found" error for the burn function.

Further Issues to Address

After correcting the typo, you may encounter another error in the mint() function. This error typically arises from attempting to reference an undeclared variable. In the mint() function, you have:

[[See Video to Reveal this Text or Code Snippet]]

Fixing the Mint Function

Here, you are trying to call _mint(to, amount);, but you have not declared to. Instead, the first argument in the mint function is account. To resolve this, you should modify the call to _mint to use the variable account:

[[See Video to Reveal this Text or Code Snippet]]

By making this change, the function properly uses the declared parameter, ensuring everything works as intended.

Summary

Here's a quick recap of what we covered:

Error Identification: Understand that "Identifier not found" can often relate to typos in your function declarations.

Corrections:

Change unint to uint in the burn function.

Ensure that the arguments of your mint function are referenced correctly.

By following these steps, you can effectively resolve common compilation issues in your Solidity work. Keep these pointers in mind when you encounter similar issues in your Ethereum smart contract development journey!