When do we spend Gas ?

[umershaikh123]

I have some questions regarding how gas works.
Q1-) Does it cost any gas if a function execution failed at a certain point due to any reason even if we did some computation in it or it only cost gas only if a function runs successfully on blockchain?

Q2-) Consider the following function. Do we lose any gas in changing 'a' value to 5 then again to 0 since require condition failed ?
int a = 0; // State vairable

function() {
a = 5; // changing state variable 'a' value to 5
require("...."); // Require condition failed
}

[alymurtazamemon]

@umershaikh123 You both questions answer is same, It will deduct the computation cost gas and return the remaining gas if fails.

[krakxn]

Hey, I am assuming you are a curious one - you should look at my advice posted in here. It is a solid read for beginners, especially for your gas doubts.

You will be able to answer your own questions after going through this, of course, if there are doubts I can explain. But try to answer yourself.

#1219

Hope this helps!

[umershaikh123]

awesome I will definitely check out the article and give you feedback