Interact with Your Program

Your counter program is live on Solana Devnet. Now let's call its instructions and watch the on-chain state change in real time.

What You'll Do

1. Initialize a counter account — creates a new account owned by your program
2. Increment the counter — modifies the on-chain state
3. Decrement the counter — see your custom error handling in action

Understanding the Data

The Program Explorer below shows two views of your counter account:

Parsed Data

The human-readable version: count: 3

Raw Data (Hex)

What's actually stored on-chain:

[a8 fc 0b 1f 05 77 32 45 | 03 00 00 00 00 00 00 00]
 ^^^^^^^^^^^^^^^^^^^^^^^^   ^^^^^^^^^^^^^^^^^^^^^^^^
 discriminator (8 bytes)    count: 3 (u64 LE)

The discriminator is Anchor's way of identifying account types. It's the first 8 bytes of sha256("account:Counter"). Every Anchor account starts with this — it's how the runtime knows it's looking at a Counter struct and not random data.

The count is stored as a u64 in little-endian byte order. The value 3 is 03 00 00 00 00 00 00 00 because the least significant byte comes first.

Try This

1. Click Initialize — watch the discriminator bytes appear
2. Click Increment 3 times — watch count change from 00 to 03
3. Click Decrement down to 0, then try decrementing again
4. See your #[error_code] Underflow in action!

Teaching moment: When you decrement below zero, your custom error Cannot decrement below zero is enforced by the Solana runtime. This is your code running on a real blockchain, enforcing rules you defined.