Creation-time setup differs from later runtime calls.
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Setting up a classroom scoreboard once is different from updating its score during each lesson.
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A valid counter call, step by stepStep 1 / 4
This example begins with count zero and a request to call increment(). No real contract is deployed.
This example begins with count zero and a request to call increment(). No real contract is deployed.Execution follows the code’s input and permission rules. A website button is not the access-control mechanism.The function reads zero, calculates zero plus one, and writes one to persistent storage.The accepted state contains count one. Later reads can inspect it. Events are emitted only if the code implements them.
Animated local teaching model. No wallet, RPC or live blockchain data. Some labels and hashes are abbreviated for readability.
A declaration defines the type
The contract body groups its state and behavior. Deploying an instance gives it a particular address and state under the network’s creation rules.
A constructor performs initialization
The constructor runs during creation. Its parameters can establish initial values or permissions. Those choices are part of the deployed instance’s context.
It is not an ordinary later function
The constructor’s creation-time logic is not exposed as a callable runtime method named constructor. Upgradeable architectures often need a distinct initializer pattern with separate safety requirements.
Read deployment arguments
Two instances from similar source can begin with different values. Inspect constructor inputs and deployment results rather than assuming the source text alone supplies every instance-specific fact.
Read the example
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
contract LearningExample {
uint256 public count;
constructor(uint256 initialCount) {
count = initialCount;
}
}
The constructor argument determines this instance’s starting count.
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Can a deployed instance’s constructor be called again as an ordinary external function?
It is creation-time logic, not a normal runtime entry point.