last_hash = block.hash.clone();

[moaiad1]

thanks for your efforts and time , I have a warrning when I run cargo as it couldn't read last hash I couldn't figure the issue that cause the problem as well as Failed to add block: InsufficientInputValue' where should the value stored:
please check the result

warning: value assigned to last_hash is never read
--> src/main.rs:63:5
|
63 | last_hash = block.hash.clone();
| ^^^^^^^^^
|
= note: #[warn(unused_assignments)] on by default
= help: maybe it is overwritten before being read?

warning: hash (bin "blockchain") generated 1 warning
Finished dev [unoptimized + debuginfo] target(s) in 0.12s
Running target/debug/blockchain
Mined genesis block Block[0]: e2937e782fc68a1a0f8f71830f69919136139f6f956fda1e6999f57327070100 at: 1651809036733 with: 1 nonce: 3458
Mined block Block[1]: cb8add22253b754895c232b4ca65f57dcbb42b1ebdb5bd80242e4fdea6b50500 at: 1651809036998 with: 2 nonce: 4312
thread 'main' panicked at 'Failed to add block: InsufficientInputValue', src/main.rs:65:41
note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

thanks for the nice topic

[ClementCauffet]

Hi Moaiad,

Regarding the last_hash warning, the compiler is trying to tell you "you're modifying this variable but do nothing with it after -> you might not need to modify it"

Two solutions for this :

1. add a third block to the blockchain -> doing so you'll use the variable you just modified
2. comment this line and erase the "mut" keyword when it's declared above in the code -> never modified so don't need

Regarding the InsufficientInputValue I can't reproduce the warning.
Did you modify the code? Would you mind sharing it if so?

Regards,

Clement

[brandonros]

Regarding the InsufficientInputValue I can't reproduce the warning.

I get this as well on a clean git pull

$ cargo run --release
warning: value assigned to `last_hash` is never read
  --> src/main.rs:63:5
   |
63 |     last_hash = block.hash.clone();
   |     ^^^^^^^^^
   |
   = help: maybe it is overwritten before being read?
   = note: `#[warn(unused_assignments)]` on by default

warning: `blockchain-in-rust` (bin "blockchain") generated 1 warning
    Finished release [optimized] target(s) in 0.01s
     Running `target/release/blockchain`
Mined genesis block Block[0]: 3195234a06cae70ced0cfa30a58c0039fe50bda3ec577d4f185ac19065a90800 at: 1686695216394 with: 1 nonce: 1942
Mined block Block[1]: 54f7007a87674707a068a0ac7c3dcd2291601b3e93855cefa680ce097a680b00 at: 1686695216396 with: 2 nonce: 5318
thread 'main' panicked at 'Failed to add block: InsufficientInputValue', src/main.rs:65:41
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

I added some logging:

Transaction { inputs: [Output { to_addr: "Alice", value: 50 }], outputs: [Output { to_addr: "Alice", value: 360 }, Output { to_addr: "Bob", value: 12 }] }
input_value = 50 output_value = 372
thread 'main' panicked at 'Failed to add block: InsufficientInputValue', src/main.rs:65:41

[brandonros]

In the video it's 36, in the code it is 360. Guessing it's a typo.

[jadestone-web3]

In the video it's 36, in the code it is 360. Guessing it's a typo.

sure，it‘s right