The ERC20 standard only defines the interface APIs—the implementation should be written according to your needs. There are different ways of using the implementations that are available. The most updated and best place to look for the ERC20 implementation is the OpenZeppelin library of Solidity smart contracts. We have taken a part of the implementation from the OpenZeppelin library and will use it in this chapter.
There are some implementations present without using the SafeMath library. However, we recommend using the version with SafeMath library, as it's easy to understand and integer overflow will not be caused when using the SafeMath library for mathematical operations. Whenever you are writing a contract that has mathematical calculations, ensure that you use the SafeMath library in order to write bug-free contracts.
To give you an overview...
