Why there's no concept of Null initialization to an unsigned integer in solidity?

Question

I was writing a code my unsigned-integer value initialized as 0 as shown below

My code:

// SPDX-License-Identifier: UNLICENSED

pragma solidity >= 0.5.0 < 0.9.0;

contract PT_StateVariable

{

    uint256  public age ;
}

Deploy tab

But when I tried to give it a NULL, it gave an error.

Why there's no NULL concept (like in C++) been used in Solidity?

Answer 1

In Solidity doesn't exist the concept of 'NULL' like in C++,C#,Java,... The documentation say this:

The concept of “undefined” or “null” values does not exist in Solidity, but newly declared variables always have a default value dependent on its type. To handle any unexpected values, you should use the revert function to revert the whole transaction, or return a tuple with a second bool value denoting success.

I recommend you to read documentation's section about declarations:

A variable which is declared will have an initial default value whose byte-representation is all zeros. The “default values” of variables are the typical “zero-state” of whatever the type is. For example, the default value for a bool is false. The default value for the uint or int types is 0. For statically-sized arrays and bytes1 to bytes32, each individual element will be initialized to the default value corresponding to its type. For dynamically-sized arrays, bytes and string, the default value is an empty array or string. For the enum type, the default value is its first member.

More information here.