but i only need it for linux by now so im safe

Well, theoretically you can use flatpak on Windows, but it's not implemented

what's that?

im using this now:

https://github.com/metacall/core/blob/develop/deploy/packages/pack-metacall.cmake

but i only need it for linux by now so im safe

At least w/ flatpak you're distro-independent

How return multiple variable in c ++ like python? Without class or struct

By using pointers

? he wants to return two vars at once, not return a var of any type

then use std::tuple.

Isn't it a class anyway?

He needs no class/struct

...which sounds like a strange requirement

He needs no class/struct

Depends on his/her real meaning. If he/she means not to use self-define struct, then std::tuple stands. If he/she means not to use any stuct or class, then I guess there is no known method to achieve this.

but damn! std::any looks like a cool toy

Its almost template magic :D

without templates :D

#include <iostream> #include <tuple> std::tuple<bool, int> foo(bool flag, int v) { return {not flag, flag ? ++v : --v}; } int main() { auto [f, v] = foo(true, 41); std::cout << std::boolalpha << f << '\t' << v << std::endl; return 0; } compile with C++17 standard, and it's looks really like Python.

result: false 42

no it dowsnt look like python

but this new auto decomposition of classes is ultra cool

(And adds a new burden on stl maintainers: make sure that first is in front of second in your tuple ^^)

but this new auto decomposition of classes is ultra cool

together with initializer list and package auto (structured bindings).

initializer lists are old tho

I know, but combine them together works like black magic in C++'s view.

#include <iostream> #include <tuple> std::tuple<bool, int> foo(bool flag, int v) { return {not flag, flag ? ++v : --v}; } int main() { auto [f, v] = foo(true, 41); std::cout << std::boolalpha << f << '\t' << v << std::endl; return 0; } compile with C++17 standard, and it's looks really like Python.

Wow that's magic!

Wow that's magic!

meh

#include <iostream> #include <tuple> std::tuple<bool, int> foo(bool flag, int v) { return {not flag, flag ? ++v : --v}; } int main() { auto [f, v] = foo(true, 41); std::cout << std::boolalpha << f << '\t' << v << std::endl; return 0; } compile with C++17 standard, and it's looks really like Python.

.-.

but this new auto decomposition of classes is ultra cool

looks like js

Wow that's magic!

Hmmmm, suppose map is an instance of std::map<std::string, uint64_t>, then you could use for (auto& [k, v] : map) { ... }

just like Python's for k, v in map.items(): ...

looks like js

no, does not

Hmmmm, suppose map is an instance of std::map<std::string, uint64_t>, then you could use for (auto& [k, v] : map) { ... }

const auto& pl0x

#include<stdio.h> int main() {int T,A,B,i,a[T]; printf("no of test cases: "); scanf("%d",&T); for(i=0;i<T;i++) {scanf("%d %d",&A,&B); a[i]=A+B; } for(i=0;i<T;i++) {printf("%d\n",a[i]);} return 0; } What are errors in the above code

I am not getting

What did the compiler say

Run time error

(SIGSEGV) runtime error

Interesting

Can you try initializing the array after the input is entered into T?

It looks like a compilation phase error to me

Well I'm not getting any runtime error on my compiler?

But you got runtime error?

What version of clang are you using?

C(gcc 6.3)

Can you try initializing the array after the input is entered into T?

Let me try in this way

If I am not wrong, SIGSEGV is a signal for segmentation fault so that's related to incorrect memory referencing.

C(gcc 6.3)

Maybe try copying the printf within the second loop after the assignment in the first loop

First of all, try to figure out **who** causes the runtime error

#include<stdio.h> int main() {int T,A,B,i,a[T]; printf("no of test cases: "); scanf("%d",&T); for(i=0;i<T;i++) {scanf("%d %d",&A,&B); a[i]=A+B; } for(i=0;i<T;i++) {printf("%d\n",a[i]);} return 0; } What are errors in the above code

Two errors.. Size of array must be given when declared Second.. Space between two %d in scanf function

Maybe try copying the printf within the second loop after the assignment in the first loop

I didn't understand😕

a screenshot please

Not a screenshot of your code but what the compiler complaint

I done this in my mobile in website Code Cheff so it may not be clear

Two errors.. Size of array must be given when declared Second.. Space between two %d in scanf function

For the second error you mean if the person does not enter the numbers with the space in between because I don't see why it's wrong

For the second error you mean if the person does not enter the numbers with the space in between because I don't see why it's wrong

Yess

Two errors.. Size of array must be given when declared Second.. Space between two %d in scanf function

In first error if I don't give the size the compiler is saying size must be declared

In first error if I don't give the size the compiler is saying size must be declared

Yes but size must be a constant not a variable

I done this in my mobile in website Code Cheff so it may not be clear

It makes sense now. Just try the code on your local compiler first. You will get meaningful info

How can we declare exact size when size depends on in put T

Malloc or vla

For the second error you mean if the person does not enter the numbers with the space in between because I don't see why it's wrong

There is always a space or newline char or tab between two number Try by removing spaces once.

How can we declare exact size when size depends on in put T

Either by dynamic memory allocation Or you can simply give large no say ar[1000] depending upon the constraints

Oh hmm when I copied it over and tested it out the space was inserted between the format specifiers that's what maybe causing the issue as well.

#include<stdio.h> int main() {int T,A,B,i,a[T]; printf("no of test cases: "); scanf("%d",&T); for(i=0;i<T;i++) {scanf("%d %d",&A,&B); a[i]=A+B; } for(i=0;i<T;i++) {printf("%d\n",a[i]);} return 0; } What are errors in the above code

Before you can figure out the size of the array a, say T, you cannot declare it. int T, a[T]; Suppose you are your compiler, how many slots will you reserve for array a?

With AddressSanitizer, you'll get more information about memory violation. $ env LD_LIBRARY_PATH="/opt/gcc/gcc-8.2.0/lib64:$LD_LIBRARY_PATH" ./a.out no of test cases: 3 1 2 3 4 5 6 ================================================================= ==21038==ERROR: AddressSanitizer: dynamic-stack-buffer-overflow on address 0x7fff7264b260 at pc 0x000000400cc1 bp 0x7fff7264b230 sp 0x7fff7264b228 WRITE of size 4 at 0x7fff7264b260 thread T0 #0 0x400cc0 in main (/home/liam/test/c/a.out+0x400cc0) #1 0x7f812573fb14 in __libc_start_main (/lib64/libc.so.6+0x21b14) #2 0x400978 (/home/liam/test/c/a.out+0x400978) Address 0x7fff7264b260 is located in stack of thread T0 SUMMARY: AddressSanitizer: dynamic-stack-buffer-overflow (/home/liam/test/c/a.out+0x400cc0) in main [0/3848] Shadow bytes around the buggy address: 0x10006e4c15f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x10006e4c1600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x10006e4c1610: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x10006e4c1620: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x10006e4c1630: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 =>0x10006e4c1640: 00 00 00 00 00 00 00 00 ca ca ca ca[cb]cb cb cb 0x10006e4c1650: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x10006e4c1660: f1 f1 f1 f1 04 f2 f2 f2 f2 f2 f2 f2 04 f2 f2 f2 0x10006e4c1670: f2 f2 f2 f2 04 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 0x10006e4c1680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x10006e4c1690: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Shadow byte legend (one shadow byte represents 8 application bytes): Addressable: 00 Partially addressable: 01 02 03 04 05 06 07 Heap left redzone: fa Freed heap region: fd Stack left redzone: f1 Stack mid redzone: f2 Stack right redzone: f3 Stack after return: f5 Stack use after scope: f8 Global redzone: f9 Global init order: f6 Poisoned by user: f7 Container overflow: fc Array cookie: ac Intra object redzone: bb ASan internal: fe Left alloca redzone: ca Right alloca redzone: cb ==21038==ABORTING

I'm able to run his code without error on gcc8. I think they msut be using dynamic memory allocation of some sort.

Check this line: 0x10006e4c1640: 00 00 00 00 00 00 00 00 ca ca ca ca[cb]cb cb cb ca means memory before actually allocated, and cb means memory after actually allocated. As you can see, since you allocate a[T] before T is correctly initialized, it's zero, and hence the size of a is zero (`cb`s is exactly after `ca`s). When you are trying to write something in `a[0], the sanitizer detects that you are trying to dereference `cb, and reports the error.

I'm able to run his code without error on gcc8. I think they msut be using dynamic memory allocation of some sort.

No. It's undefined behavior. No runtime error doesn't mean the code is correct.

No. It's undefined behavior. No runtime error doesn't mean the code is correct.

Yeah gcc can hide the errors sometimes

Can you try initializing the array after the input is entered into T?

Anyways I also suggested him to try the same thing at first

I done this in my mobile in website Code Cheff so it may not be clear

coding on a phone is eww

Yeah gcc can hide the errors sometimes

It's not GCC... Check this code: #include <stdio.h> int main() { int before1 = 0; int before2 = 0; int a[0]; int after1 = 0; int after2 = 0; printf("before: %d %d, after: %d %d.\n", before1, before2, after1, after2); a[0] = 42; printf("before: %d %d, after: %d %d.\n", before1, before2, after1, after2); return 0; } I declared an array of int of size 0, and a out-of-boundary write happened after that a[0] = 42;. The result might be: before: 0 0, after: 0 0. before: 0 0, after: 0 42. See? There might be no run time error, but the result of the program is wrong. As you could see, after2 is modified unexpectedly to 42.

coding on a phone is eww

LOL 😂

LOL 😂

No

just dont do it

It's not GCC... Check this code: #include <stdio.h> int main() { int before1 = 0; int before2 = 0; int a[0]; int after1 = 0; int after2 = 0; printf("before: %d %d, after: %d %d.\n", before1, before2, after1, after2); a[0] = 42; printf("before: %d %d, after: %d %d.\n", before1, before2, after1, after2); return 0; } I declared an array of int of size 0, and a out-of-boundary write happened after that a[0] = 42;. The result might be: before: 0 0, after: 0 0. before: 0 0, after: 0 42. See? There might be no run time error, but the result of the program is wrong. As you could see, after2 is modified unexpectedly to 42.

that's a gcc extension

that's a gcc extension

It's not an extension... It's undefined behavior.

it wont work in other compilers unless they support the same extension