Thread by @developerPrasad

Just completed level 1 on #cryptozombies

share.cryptozombies.io/en/lesson/1/sh…

Some learnings from a java developer perspective 👇

#Solidity #Ethereum #Web3 #Blockchain #Java #javascript

The naming convention is the same as java.
We have few extra datatypes like
🔲 uint (Unsigned integer)
🔲 struct (Similar to a class in java) - Doesn't have a constructor

uint - Unsigned Integer - int data type that only stores non-negative integers i.e 0 and positive integers.

For e.g, if an int can store 256 numbers, the range of int will be from -128 to 127. But the range of uint will be 0 to 255.

For calculating an exponential, there is an extra operator **

uint x = 5 ** 3;
The value of x will be 125.

In java, let us assume we have a person class and for storing the address we use a separate class that has houseNumber and streetName. We can use struct here

struct Address {
uint houseNumber;
string streetName;
}

There is no new keyword in solidity. If we want to create a new address, the syntax is

Address myAddress = Address(1,"Baker street");
We can push this into an array (similar to javascript)

Address[] addresses;
addresses.push(myAddress);

Functions - all functions are by default public in solidity - Which means anyone (or any other contract) can call your contract's function and execute its code.

The function declaration is slightly different - In my opinion, it is a combination of java and javascript styles

Example:
We need to use the 'function' keyword at start followed by name of function.

The main difference is we shift the public/private keyword & return type to the end of the declaration

function _addNumbers( uint _x, uint _y) private returns (uint) {
return _x + _y;
}

We can add one of the 2 keywords view/pure to function declarations

view - If the function doesn't actually change state e.g. It doesn't change any values or write anything

pure - If the function is not even accessing the data from our contract - e.g. helper functions

TypeCasting is very similar to java

We can declare and fire events as per the requirement. Example

event FindSum(uint x, uint y, uint result);

function _findSum(uint _a, uint _b) private returns (uint) {
uint result = _a + _b;
emit FindSum(_a,_b,result);
return result;
}

Overall, it was a good learning experience. The concepts are explained clearly.
@loomnetwork

#cryptozombies
#java #Solidity #Web3 #Blockchain