Mastering Blockchain Programming with Solidity

The totalSupply function

The totalSupply() function returns the total supply of the tokens. This means that the sum total of token balances of all of the token holders must match the total supply. The state of the total supply is maintained in a state variable, which gets increased or decreased upon minting new tokens (creation of new tokens) or burning (destroying existing tokens). The transfer() or transferFrom() functions do not update the total supply of the token.

The following is the API of the totalSupply() function:

function totalSupply() external view returns (uint256);

The function call returns the total supply of the token as uint256. The following is the code that just returns the value of the totalSupply_ variable:

function  ...