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So now let's look at how we can accept and use command line arguments.

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The first thing we need to do is bring standard.

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In var into our scope.

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So inside of Main, let's now create a vector called args.

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So let args and then we know it's going to be a vector of string and we can say environment that's what

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a short for args and then skip one and I'll explain that in a second and then we have a collect iterator

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for us.

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So we're going to use Skip one because we run our program.

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That is actually the first argument.

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But we don't want that one.

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We want everything that follows our.

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Program name.

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And that's going to give us the rest of everything else.

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So we also know that we want it.

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We want for arguments.

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We don't want any less.

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And we also don't want anymore.

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So we want our length.

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Basically two equal four.

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So if it does not equal four, then we want to print our help out for us.

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So now we can remove this.

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And now we can also say.

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Frontline and we want to provide them a useful error message.

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Wrong number of argument is given expected for.

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Got another.

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Value pressed in.

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So we'll say air.

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And then we want it to be read and we also want it to be bold.

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And then we want to look at how many argument we actually were printed out.

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And then if we get to this point, we don't want our process to continue, so we want it to actually

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exit.

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And then we wanted to exit with air code one, which signifies.

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That are.

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Program did not.

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Run successfully.

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So now let's do a couple of runs.

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So we'll say cargo run and let's see what it does.

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So we see we have find and replace.

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Good.

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So that was our print help function being called and then we see error wrong number of arguments given

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expected four got zero and now we see also our process didn't exit successfully which is right here.

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So great.

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So we see that it was running correctly.

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So now let's try running it and give it four arguments.

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So we'll say ARG one or two, ARG three and ARG four and everything.

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Ran correctly.

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So obviously we don't have the logic in yet to handle our arguments, but this is a great start to our

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program and now we know how we can utilize accepting arguments in from the command line and making sure

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that they are being stored correctly inside of our argument, our args vector.

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So now let's look at how we can actually structure our program correctly and separate all of this logic

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into different files.

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That way, we only use Main to run our program and not handle all of our core logic.