Solidity Tutorial For Developers - Let's Create a Smart Contract (Hands-On Project)

In this video, we'll be learning Solidity. Not just the syntax, data types, and other boring concepts when isolated by themselves, but we'll be learning all these in the context of creating a fun smart contract. It will be practical and hands-on.
Solidity is a statically typed language designed for creating smart contracts on the Ethereum Virtual Machine.
It's your entry point for learning to write Smart Contracts.
Note that this tutorial requires some basic coding knowledge. I won't be teaching what loops or functions are or how they work, but instead will be showing you how they are written in Solidity in the context of a real Smart Contract.
By the end of the video, you'll have a fully functional smart contract as well as the knowledge to start creating your own.
Enjoy.
Github code - gist.github.com/rodgtr1/427a6...
Check out my BRAND NEW Web3 Course - geni.us/GGTRi0p
Timestamps:
Intro - 0:00
Smart Contract Overview - 0:42
Tutorial - 2:15
Solidity Cheatsheet - 55:07
A UI for our contract? - 56:08
For an in-depth Solidity course, this is my one recommendation:
geni.us/YoumAXH
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[@worldtrends3296]

This is the best solidity tutorial online, no much talk, just straight to the point with a full contract built.

[@marjuksajid]

Thank you so much. It is very helpful. I am watching from Bangladesh 🇧🇩

[@lolaaaa864]

I believe this is the best video about Solidity on KZbin

[@gaganborra7593]

Man! this is the first solidity tutorial that I have watched till the end! Every sec of it is interesting ! Thanks for the video!

[@saintgabriel0]

The first snart contract tutorial I watched to the end. Thanks so much for the video .

[@HelghastSon]

I cant thank you enough for this tutorial. So easy to follow, you explain everything in great detail, and your voice is extremely pleasant to listen to. I feel so much more confident tackling solidity with this video. Thank you so much, king.

[@plb7459]

Love the way you teach, easy to understand with examples. Would love to see more solidity smart contract projects please!!

[@TravisMedia]

Thanks Paul, more to come! Here's the most recent kzbin.info/www/bejne/n3ewfoKQp6d5sLc

[@Rahulkp220]

No fluff Solidity tutorial! Thanks a ton! Subscribed.

[@bigcoryjones2126]

I used this video to compile my 1st contract without any coding experience. you my friend are brilliant. When I say without any coding experience I do mean literally 0. I was computer illiterate 2 weeks ago.

[@TheOGDesigner]

Thanks a lot for such a neat an in-depth tutorial! This was actually a great real-life use case for a smart contract while learning the basic concepts 💯💯

[@rocketrobin3393]

Just found your channel. You are the first one to really explain it well and create something useful. Much appreciated!

[@themomentier]

So true this simple video is much simpler and straight forward than bunch of paid once. thanks

[@demiann4160]

Yes, exactly. If I make a statement about web3 is for the lack of high-quality training. This is an exception.

[@anupamat.c5181]

very true

[@marcelom.5672]

Hands down best tutorial on the matter, thanks for putting this out!! Glad to have found it. What would you recommend next after this? Any other videos? Thanks and have a great weekend!

[@shidharthraj9310]

Really loved the way you teach solidity. Can you please make more such videos on Blockchain Development and solidity...👍.

[@NicolasG-pc8un]

This is a great video. There's one bug though, you need to reset the amount to 0 after a kid withdraws, otherwise they would be able to repeatedly call withdraw() and take other kids funds.

[@solidityacademy]

That was an amazing video packed with valuable information! 👏 Thanks a lot! 🙌

[@MakeYouSuperhuman]

Just Amazing , best Tutorial on KZbin.

[@Eche0001]

This video is really simplified and knowledgeable. thanks I really appreciate. Can you please make more videos on Solidity

[@bartosz13]

First tutorial i made to the very end thank You for this

[@anikalee3471]

Hey Travis! It'd be great if you could do a part 2 to this tutorial on how we can link it up to a frontend like Angular. Thank you so much for this tutorial and I hope you'd consider making follow-up tutorials for this! :-)

[@salmanabdulaziz7552]

From the middle east region, Great video !!. Need more examples and sample hands on

[@aktoriukas]

What a great tutorial! Thanks for that.

[@javierdash1]

just love it. Super well explain. Hope you have lots of visits because it is a great tutorial!!

[@jackwee4921]

Ya agree

[@EnglishRain]

Thank you for your excellent high quality content!

[@cz8986]

God, such a good and easy to understand introduction to solidity ! Thx a lot !

[@TravisMedia]

Glad it was helpful!

[@lolaaaa864]

Very clair but I did get everything .. I ll try the udemy course .. Thank you for sharing

[@mjmj007a]

Great Video and Thank You !

[@mhzboxing1759]

Wow I love the way you teach Solidity. You should do a TedTalk

[@montof9195]

Question: Would it be a good compromise for gas to use a storage mapping for (address => Kid) instead of looping multiple times with a for loop in each function?

[@MrMahesh7001]

Excellent video on Solidity Travis, thank you for your video. Could you please share or explain the front end integration of this CryptoKids project, please? Really interesting to see the integration part of this smart contract to UI. That's really greatly appreciated. Thank you.

[@mahendranath2504]

Thank you so much 😊

[@hereticsaint100]

Yes, do the JS front end tutorial!

[@salmanabdulaziz7552]

Dear Travis, Can you teach us the in same way the last part of graphical version of same program. It would be nice to learn that also. How graphically we can present contracts and have hands on session.

[@khizerhayyat549]

Hi Travis! thanks for the amazing content but don't you think that using array for the kids will be the cause of high gas when you will find the index through a loop and event the if condition inside. what would you say about mapping? something like mapping(address => Kid) public kids;

[@TravisMedia]

Hi Khizer! Thanks for the input and you're exactly right. I think I mentioned about the gas fees, though, in the video. I was mainly using the array for the teaching aspect of Solidity. But yes, a mapping just like you said is a much better option. I used that instead in my latest Bike Rental App video as it is much more efficient. Thanks again for the input.

[@sujeewa8067]

Thanks a lot man!

[@m4_thednblab397]

im getting an error that you don't seem to be getting, which is stopping me from being able to interact with the SC but outside of this, great tutorial, thanks for your time!

[@skyking4997]

Perfect thanks

[@SuperDividenz]

can you deploy to block chain? possibly on other evm chains?

[@Inderashah007]

Great 👍🏽

[@kichirmichir2730]

nice job....

[@jackdelagrange1519]

Hey Travis, great video, will you be posting more solidity or blockchain /crypto content?

[@TravisMedia]

What would you like to see?

[@jackdelagrange1519]

@@TravisMedia I think many people want to learn about crypto, blockchain , web3, etc. You have a clear way of explaining these complex and important subjects. Thanks again for the solidity info!

[@vladusa]

You forgot to specify range of dates. If someone puts a '0' for time to withdraw, things go wrong. Maybe make an initial check for timeToWithdraw > timeOfContract

[@adityasai550]

I think it's not a problem. In that case, we can simply assume the kid can withdraw money as soon as their parents deposit it.

[@vladusa]

@@adityasai550 exactly. This was what my comment stated. withdrawTimestamp - entryTimestamp.

[@Chrisadynowski]

Great vid ! I have question regarding lists , you shows something like : uint[5] names; and here for example : names.push("Travis"); I think this is wrong becasue list is type of uint not string soooo is should be string[5] names; names.push("Travis"); and with uint[5] age; age.push("34"); Something like that ? I am not sure it was for me just weard that list is type of uint and you want to push there strings :D If I am wrong please correct me !

[@TravisMedia]

Nope you’re right. Thanks for pointing that out. Mainly it was a passing/quick example of how you would add to a list so I didn’t consider the type closely.

[@pavspy3489]

Hi. Can someone plz help me understand, around 25 min, mark. Why are funds being added to the child account from the same child's address?

[@gugapilar3135]

Continue postando os videos! Te desejo muita sorte com o teu canal! Siga postando os viideos! te desejo toda sorte com o teu canal!

[@dennyage4791]

One suggestion: please use larger font size and attach github file links

[@TravisMedia]

Appreciate the suggestions. Will put the github file link in the description tomorrow.

[@vncntjms]

Can we use the address itself as index of the array? So we don't have loop through all addresses just access it like kids[walletAddress]

[@TravisMedia]

Yes that’s a much more efficient approach. But wanted to use an array for the beginner tutorial.

[@vncntjms]

@@TravisMedia understood. thank you

[@codyshipley3900]

Travis, Is there anyway you can have a look at a contract and help me with something?

[@mokho3027]

around 15:00, why cant we simply add our 'struct' as a parameter to our function instead of putting all those variables that are in struct?

[@nouraldeen9254]

Is this video useful for beginners (first time solidity and smart contracts)!?

[@TravisMedia]

Yes. Next step after this is here: kzbin.info/www/bejne/goSvZ2yIfMqEgpI

[@rndom-fact]

Can someone without a prior knowledge in programming learn Solidity? How difficult is it?

[@ch453skipper2]

For once I have completed an entire tutorial without taking a break and actually understood something

[@EzamZaidi]

Maybe I am wrong, but the contract does have a lot of flaws. 1. I can transfer eth to even those addresses which are not even added as kids.

[@TravisMedia]

You can transfer to any address, yes. In a real contract there would need to be a condition for that for sure. However this was an introductory tutorial to Solidity and a contract for demonstration only.

[@codefactor]

I know it's just a tutorial project - but can't help but point out that kids can withdraw all the money by pressing withdraw button multiple times!

[@ryanz67]

I don’t see how this is the future tbh

[@spotshortmanipulators4721]

Let 's Do Another Function...

[@lyon8539]

How much you earn from a writing smart contract?

[@zackd7597]

I can't be the only one who finds coding difficult lol

[@ballinwith]

Would you like to join my team as a developer? I’m looking for people who can conduct smart contracts

[@tsunningwah3471]

zhichi

[@mexicanwhotriestosneakinto921]

why are you copying traversy media you are the fake traversy media

[@TravisMedia]

kzbin.info/www/bejne/h2baaqVul9d4Z5I

[@dineshrambabukushwaha4757]

kids[i].amount = 0; once it is transferred to wallet of the kids ? Correct me , If i am wrong here. Because I see for the same kid, if the amount transferred again and withdrawal cause issue.

[@gaganborra7593]

Yea! This should be added too! or else jane's gonna rob everything 😂

[@maakayp]

Hi Travis i need help am stuck, // SPDX-License-Identifier: GPL-3.0 pragma solidity ^0.8.7; //owner Dad contract CryptoKids { constructor() { owner = msg.sender; } } From Solidity, Declaration Error: undeclared Identifier. owner=msg.sender ^^^^^^

[@anandrai9059]

You have to write address owner ; before owner = msg.sender;