用户账户如何持有ERC20代币？众筹合约场景下的技术问询

Hey there, let's unpack this step by step because it's easy to mix up how ERC20 token ownership works versus how crowdfunding contracts track purchases.

First, let's refine your initial understanding and fill in the key gaps:

• You’re correct that when user 0x1 sends ETH to crowdfunding contract 0x2, the contract will track 0x1's token purchase (usually in a userPurchases or similar storage variable). But the critical piece about ERC20 tokens is that "holding" them doesn’t mean the tokens are stored directly in your wallet address—ownership is always recorded in the ERC20 token contract’s storage.

Two Common Crowdfunding + ERC20 Setups #

1. The crowdfunding contract is the ERC20 token contract #

If contract 0x2 was deployed as an ERC20-compliant contract (meaning it implements all required methods like balanceOf, transfer, etc.), then when 0x1 buys tokens, the contract doesn’t just log a purchase—it updates its core balances mapping (a mandatory part of ERC20 standards) to assign the token amount to address 0x1.

In this case, user 0x1 "holds" the tokens because the ERC20 contract (0x2) explicitly records their ownership in its storage. When 0x1 checks their wallet, the wallet will call the balanceOf(0x1) method on 0x2, fetch the returned value, and display that as their token balance.

2. The crowdfunding contract interacts with a separate ERC20 token contract #

Many projects split logic: deploy a standalone ERC20 token contract (say, 0x3) and use 0x2 only for crowdfunding rules. Here’s how that flow works:

• 0x1 sends ETH to 0x2
• 0x2 validates the payment, calculates how many tokens 0x1 deserves
• 0x2 calls the mint(0x1, tokenAmount) method on ERC20 contract 0x3 (assuming 0x2 has mint permissions)
• Contract 0x3 updates its own balances mapping to assign the tokens to 0x1

Here, 0x1’s token ownership lives in 0x3, not 0x2. Their wallet will query 0x3’s balanceOf(0x1) to show their holdings.

Addressing Your Unfinished Question (My Best Guess!) #

Since your question cut off at "若……", I’m assuming you might be asking something like:

"If the crowdfunding contract only tracks purchases in its own storage, are those 'tokens' even valid ERC20s?"

Or:

"Why doesn’t the crowdfunding contract just send tokens directly to my wallet right away?"

To answer the first: If 0x2 isn’t an ERC20 contract, its internal purchase records are just bookkeeping—those "tokens" aren’t transferable or wallet-compatible until the project migrates them to a proper ERC20 contract (e.g., after the crowdfunding ends, 0x2 would mint real ERC20 tokens to all users based on its internal logs).

To answer the second: Some crowdfunding contracts hold tokens in escrow until the funding goal is met. If the goal isn’t reached, they refund ETH and never mint tokens. Tracking purchases internally first lets the contract handle these edge cases before issuing actual ERC20 tokens.

内容的提问来源于stack exchange，提问作者Test1 Test2