The 6 key functions of ERC20 Token Standard

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Now we can start writing the functions defined by the ERC20 standard. A set of 6 mandatory functions for the creation of the token and its subsequent integration into marketplaces and crypto wallets. All ERC20 tokens have at least these 6 functions:

• totalSupply: This function specifies the total number of token supply. Once this limit is reached, the contract will refuse to create more tokens.
• balanceOf: This function is used so that the contract returns the number of tokens that a wallet has.
• allowance: Function that checks if a user has enough tokens so that they can send them to another user.
• transfer: The function that allows you to obtain a number of tokens from the initial supply and give them to a user.
• approve: Function that checks if the contract can send a number of tokens to a user taking into account the total supply of tokens.
• transferFrom: This feature enables the transfer of tokens between different users.

In addition to this, we will implement 2 additional events. A first event that notifies when a quantity of tokens passes from a source to a destination and a second event that notifies the approval of the allowance function.