I can help you understand this fragment of the code and explain what is going on.
Ethereum signature
In Ethereum, the functions are declared using the “function” keyword, followed by names, parameters, feedback and all necessary keywords. The signature of the function is defined as follows:
Returntype: Data type of value returned by the function.
Params: List of parameter names, their types and optional default values.
Name: Name of the function.
Keywords: optional keywords that can be used to modify the behavior of the function.
code
Let’s analyze the delivered code:
`Solidity
Cast Sig "Workmydirefulower (Uint256, Uint256)"
0xa9059cbb ...
Here is a failure:
Sig: This is a key word in solidity, which means” signature “. Used to declare functional signatures.
" Workmydirefulower ": This is the name of the function that can be considered a" name ".
- (Uint256, Uint256)
: These are the names and types of parameters. The first two parameters (UINT256) are 32-bit integers, while the third parameter (also" Uint256) is also a 32-bit integration number.
%: This keyword indicates that ‘sig’ should be treated as “name”, not an address or type.
** What’s going on?
The code throws “sig” Roboczidirefulower “to have a signature” (“Workmydirefulower”, 32, 32). Here’s what is happening:
- The first parameter is now a literal string “” Workmydirefulower “, which can be treated as an address.
- The second and third parameters are still the type of
Uint256, which means that 32-bit integers are not signed.
** Why does it make sense?
In solidity, the names of the function are usually used as addresses or types when defining a new function. After defining the functions of the same name, but different types of parameters and data types, it is often called “overload” or “hidden parameter”.
Through the casting “SIG” Roboczidireaphulower “(Uint256, Uint256)Basically, we create an overloaded version of the original signature of the function. This allows us to use the same name for another set of parameters, and at the same time is treated as an address or type.
Examples of use
Here is an example that shows this concept:
Solidity
Pragma solidity ^0x6ba95ecddd5af9f3cde8b4cf2bfabe3ed452e1cd;
Myfunction function (uint256 _x, uint256 _y) public {
// ...
}
Another MyFunction function (uint256 _X, uint256 _y) public {
// ...
}
Uint256 sig = myfunction ("Workmydirefulower", 0x1234567890123456789);
Another function (SIG, 0x2345678901234567);
In this example, we define two different functions of Myfunction and” Anothmyfunction “, both with the same name, but different types of parameters and data types.
When we throw “SIG” Workmydirefulper “, we get an address that can be used to call any function. After transferring this address to the “different”, it causes the second version of the function that uses the original type of parameter and data type.