but constexpr are typesafe, and thats one of the most important features about c++

My point is, const is enough for a novice

mh

i guess we have different opinions on that :)

Yeah, then we say, that it is good to have a lot of little simple functions. We do int calc() { int r{ 0 }; // some shit return r; } constexpr int important_var{ calc() }; // duh

Thing is, we can't explain constexpr as "just slap it somewhere, it's a good stuff"

Thing is, we can't explain constexpr as "just slap it somewhere, it's a good stuff"

I think constexpr is even easier to explain than plain const

I think constexpr is even easier to explain than plain const

Rly? Then say what type s has in constexpr char* s{ "str" };

Yeah, then we say, that it is good to have a lot of little simple functions. We do int calc() { int r{ 0 }; // some shit return r; } constexpr int important_var{ calc() }; // duh

And why this is a compilation error

To a person who isn't sure how to use if

Rly? Then say what type s has in constexpr char* s{ "str" };

constexpr doesn't really say anything about the type like const does. It just tells the compiler that the value has to be known at compile time

And why this is a compilation error

Because you didn't mark the function as constexpr

constexpr doesn't really say anything about the type like const does. It just tells the compiler that the value has to be known at compile time

constexpr implies const constexpr int f{ 3 }; // f has type const int

Because you didn't mark the function as constexpr

Now list all the conditions a func must meet to may be evaluated at compile time

It may be harder than virtual functions

Now list all the conditions a func must meet to may be evaluated at compile time

You can find them in cppreference. In C+11 were restricted to a single return statement, but they relaxed that in C++14. You can do pretty much anything that doesn't involve dynamic allocations

Now list all the conditions a func must meet to may be evaluated at compile time

Remember, we're talking about novices: people, who hasn't even heard about classes e.g. They're struggling with unformatted text output

It's as simple as "constexpr implies compile time execution instead of runtime"

If you have constexpr int sum(int lhs, int rhs){ return lhs + rhs; }, what you're telling the compiler is "Hey, do this at compile time if you can"

In C++20 we will have inmediate functions, which will be marked as consteval. This forces the function to be executed at compile time

You can find them in cppreference. In C+11 were restricted to a single return statement, but they relaxed that in C++14. You can do pretty much anything that doesn't involve dynamic allocations

First bullet: > its return type must be a LiteralType Okay. Let's take a look > possibly cv-qualified (da hell?) void Well, that's relatively easy to google > trivial dtor, aggregate, closure Et cetera

First bullet: > its return type must be a LiteralType Okay. Let's take a look > possibly cv-qualified (da hell?) void Well, that's relatively easy to google > trivial dtor, aggregate, closure Et cetera

One need to know hella lot terms and principles to understand conxtexpr conditions

It may sound easy for one who faced this things a lot

One need to know hella lot terms and principles to understand conxtexpr conditions

I don't even understand all of them. I just program functions normally, mark them as contexpr and wait for the compiler to tell me what's wrong and adapt as I go

Just avoid dynamic allocations and you're good to go

They're not used for everything, but if you think your function is quite simple, just mark it as constexpr and the compiler will execute at compile time everytime it can

I don't even understand all of them. I just program functions normally, mark them as contexpr and wait for the compiler to tell me what's wrong and adapt as I go

A lot of work for like fifth example after hello world

It's not that difficult. You just want to know EVERYTHING, which isn't really necessary

> mark them as contexpr and wait for the compiler to tell me what's wrong and adapt as I go That's a way actually. But what we want them to learn is const. And slapping constexpr everywhere explains neither const nor constexpr

I admit I may've crossed a line, but I do think every single word in a program should be clear to one who writes it, especially if one learns a language

Isn't the keyword constexpr clear enough to you?

Isn't the keyword constexpr clear enough to you?

It's clear as a term, but not it's usages and restrictions

Like, with C++20 we will be able to do constexpr funcs virtual and have try blocks inside

There are similar differences in 11/14

It's clear as a term, but not it's usages and restrictions

There's few restrictions. An important one is that the code can't invoke undefined behaviour, which is pretty sensible

hey guys , is there a way to buggy a directory list crawler in c++?

what?

I coded a a function to find all files , directories , and sub directories with its files , but at the moment to change it to D: second hard drive it skips some folders

C:\Users\blackleitus\Documents\xxxx\strix\Release>strix.exe D:\\poc.c D:\\things.txt D:\\blackleitus\Videos\movies\No Reservations (2007) [BluRay] [720p] [YTS.AM]\No.Reservations.2007.720p.BluRay.x264-[YTS.AM].mp4 D:\\blackleitus\Videos\movies\No Reservations (2007) [BluRay] [720p] [YTS.AM]\No.Reservations.2007.720p.BluRay.x264-[YTS.AM].srt D:\\blackleitus\Music\ C:\Users\blackleitus\Documents\xxxx\strix\Release>D: D:\>dir Volume in drive D is Bk-Storage Volume Serial Number is 7AC4-6C0A Directory of D:\ 06/30/2019 12:30 AM 1,346 poc.c 06/30/2019 12:30 AM 210 things.txt 05/30/2019 04:45 PM <DIR> blackleitus 2 File(s) 1,556 bytes 1 Dir(s) 961,850,376,192 bytes free D:\>cd blackleitus D:\blackleitus>dir Volume in drive D is Bk-Storage Volume Serial Number is 7AC4-6C0A Directory of D:\blackleitus 05/30/2019 04:45 PM <DIR> . 05/30/2019 04:45 PM <DIR> .. 05/27/2019 11:33 PM <DIR> Documents 05/22/2019 07:54 AM <DIR> Pictures 05/22/2019 12:56 PM <DIR> Music 04/25/2019 11:07 PM <DIR> Videos 0 File(s) 0 bytes 6 Dir(s) 961,850,376,192 bytes free

this is what I am talking about

what IDE are you working on?

visual studio 2019

include windows headers, put a system("pause"); at the start of main, and run it in the console, then go to vs, press ctrl + alt + p and select your program, now press any key in the console and you got a debugger attached

it works as indeed because if I change the location to D:\username\\Documents it works well

it just skipt some folders

step through the code and see why it skips it

i doubt its any mistake in the api

Only the case for global variables

Ohh!!!

Anyone could help at this question would be appreciated: https://stackoverflow.com/questions/56880708/unexpected-compile-error-in-c-passing-default-value-to-function-parameter

nice name

and nice meme

Yeah, then they might do constexpr std::string prefix{ "$HOME/myspace/" };

https://en.cppreference.com/w/cpp/string/basic_string_view

Halp fore it

before coding . learn how to ss or use github to store code , and trace error

Tanks but this exercise is finaliayed for it

?

also your error is so trivial it's not even funny

also your error is so trivial it's not even funny

I know but for me it so difficult

Hi, guys

I have results 3 error

I know but for me it so difficult

It is, you are simply too lazy to read your own code

I have results 3 error

look at the line above the highighted one

like you can't miss it

I have results

Tanks

Halp guys I have an "error" when I put the variable before it's an Ù

first show a screenshot/pastebin of your code and explain your problem

then we could help you

Ok

🙈

🙈

Ok

Sorry for the Italian

Screenshot or pastebin

Not this

It's a photo

And it's useless for us

Why?,

i already warned you to not send photos of screens

It's a photo

do a screenshot: use a program that capture your screen (or a portion of it), save it as an image, send the image here