Can anybody help me with this code? | Together C & C++ | Page 1

vernal phoenixBOT Sep 12, 2023, 10:31 AM

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@woven sundial

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supple wraith Sep 12, 2023, 10:50 AM

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can you please format your code first

vernal phoenixBOT Sep 12, 2023, 10:50 AM

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How to Format Code on Discord

Markup

```cpp
int main() {}
```

Result

int main() {}

ionic cargo Sep 12, 2023, 10:50 AM

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double x, double& y, int i, int& j
````x` and `i` are copies. `y` and `j` are references

woven sundial Sep 12, 2023, 10:51 AM

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yes that i know

ionic cargo Sep 12, 2023, 10:51 AM

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so if you modify x inside Mystery the value of the original x is unchanged

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oh wait youre saying that isn't happening

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ah right

woven sundial Sep 12, 2023, 10:51 AM

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what i mean to say is that for instance
x = 1.0;
y = 2.0;
i = 3;
j = 4;
Mystery (y,x,j,i);
this can also be represented like this also right?
Mystery (2.0, 1.0, 4, 3)

supple wraith Sep 12, 2023, 10:52 AM

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no, you can't take a mutable reference to a literal

woven sundial Sep 12, 2023, 10:52 AM

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no i mean the values are passed like this right

supple wraith Sep 12, 2023, 10:52 AM

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in a purely value-wise sense then yes you're correct

compact marsh Sep 12, 2023, 10:52 AM

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in your case

in the main :
x = 1.0;
y = 2.0;
i = 3;
j = 4;

in the function :
y = 1.0;
x = 2.0;
j = 3;
i = 4;

after the process :
x = 1.0
y = 1.0
i = 8
j = 6

you "return" j and y and put the value on x and i so result is :
x = 1.0;
y = 2.0;
i = 6;
j = 4;

ionic cargo Sep 12, 2023, 10:52 AM

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;compile

#include <iostream>
using namespace std;
void Mystery(double x, double& y, int i, int& j);
int main() {
    double x;
    double y;
    int i;
    int j;

    x = 1.0;
    y = 2.0;
    i = 3;
    j = 4;
    Mystery (y,x,j,i);
    cout << x << y << i << j;
    return 1;
}
void Mystery(double x, double& y, int i, int& j) {
    x = y;
    y = x;
    i = 2 / i;
    j = 2 / j;
}

hushed masonBOT Sep 12, 2023, 10:52 AM

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Program Output

woven sundial Sep 12, 2023, 10:53 AM

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you "return" j and y and put the value on x and i so result is :
x = 1.0;
y = 2.0;
i = 6;
j = 4;
this part i dont understand

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how did it becomes this

ionic cargo Sep 12, 2023, 10:53 AM

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Mystery (y,x,j,i); wtf

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why are you mixing up the order

woven sundial Sep 12, 2023, 10:53 AM

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the question is like this lol

ionic cargo Sep 12, 2023, 10:53 AM

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sure you don'tmean Myster(x, y, i, j)

woven sundial Sep 12, 2023, 10:53 AM

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what can i do?

ionic cargo Sep 12, 2023, 10:54 AM

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the answer isn't 1 1 8 6 though idk how you managed to get that

ionic cargo Sep 12, 2023, 10:55 AM

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hushed mason

this code results in 1 2 0 4

supple wraith Sep 12, 2023, 10:55 AM

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the original formatting has stars for multiplication

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but discord makes it italic text i guess

ionic cargo Sep 12, 2023, 10:55 AM

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ohhh

supple wraith Sep 12, 2023, 10:55 AM

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hence why I asked them to actually format their code

ionic cargo Sep 12, 2023, 10:55 AM

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stars not divides

flint moon Sep 12, 2023, 10:55 AM

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!f

vernal phoenixBOT Sep 12, 2023, 10:55 AM

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I cant understand how the answer is 1 2 6 4 when i tried dry running it in function itself it gives 1 1 86 how does it change from 1 1 86 to 1 2 6 4, isn't i pass by value. Please help

#include <iostream>
using namespace std;
void Mystery(double x, double& y, int i, int& j);
int main() {
  double x;
  double y;
  int i;
  int j;

  x = 1.0;
  y = 2.0;
  i = 3;
  j = 4;
  Mystery(y, x, j, i);
  cout << x << y << i << j;
  return 1;
}
void Mystery(double x, double& y, int i, int& j) {
  x = y;
  y = x;
  i = 2 * i;
  j = 2 * j;
}

Erik_Slam

supple wraith Sep 12, 2023, 10:55 AM

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vernal phoenix I cant understand how the answer is 1 2 6 4 when i tried dry running it in funct...

;compile

hushed masonBOT Sep 12, 2023, 10:56 AM

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Program Output

ionic cargo Sep 12, 2023, 10:56 AM

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;compile

#include <iostream>
using namespace std;
void Mystery(double x, double& y, int i, int& j);
int main() {
    double x;
    double y;
    int i;
    int j;

    x = 1.0;
    y = 2.0;
    i = 3;
    j = 4;
    Mystery (y,x,j,i);
    cout << x << y << i << j;
    return 1;
}
void Mystery(double x, double& y, int i, int& j) {
    x = y;
    y = x;
    i = 2 * i;
    j = 2 * j;
}

hushed masonBOT Sep 12, 2023, 10:56 AM

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Program Output

supple wraith Sep 12, 2023, 10:56 AM

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lol

compact marsh Sep 12, 2023, 10:56 AM

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lmao

ionic cargo Sep 12, 2023, 10:56 AM

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wow

woven sundial Sep 12, 2023, 10:56 AM

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void Mystery(double x, double& y, int i, int& j) {
x = y;
y = x;
i = 2 / i;
j = 2 / j;
}
if i put the values 2.0, 1.0 , 4 ,3 i get 1186

supple wraith Sep 12, 2023, 10:56 AM

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do you know how to use a debugger?

woven sundial Sep 12, 2023, 10:56 AM

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no

supple wraith Sep 12, 2023, 10:56 AM

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because that sounds like something you need really bad right now

ionic cargo Sep 12, 2023, 10:57 AM

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woven sundial void Mystery(double x, double& y, int i, int& j) { x = y; y = x; i =...

wait is it / or is it *

woven sundial Sep 12, 2023, 10:57 AM

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how to use it

supple wraith Sep 12, 2023, 10:57 AM

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woven sundial no

then learn to use one

woven sundial Sep 12, 2023, 10:57 AM

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ionic cargo wait is it `/` or is it `*`

woven sundial Sep 12, 2023, 10:57 AM

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supple wraith then learn to use one

where can i use one

ionic cargo Sep 12, 2023, 10:57 AM

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woven sundial void Mystery(double x, double& y, int i, int& j) { x = y; y = x; i =...

okay well this works from top to bottom

supple wraith Sep 12, 2023, 10:57 AM

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what's your IDE

woven sundial Sep 12, 2023, 10:57 AM

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supple wraith what's your IDE

codeblocks

supple wraith Sep 12, 2023, 10:57 AM

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well great it has one builtin as far as I remember

compact marsh Sep 12, 2023, 10:58 AM

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Mystery(a, b, c, d)
void Mystery(double e, double& f, double g, double& h)

your function is like that, the a goes to e the b to f ect,

in your function y goes to x, x goes to y ect

supple wraith Sep 12, 2023, 10:58 AM

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woven sundial codeblocks

can you click on the left of line numbers next to your file to put a red dot?

ionic cargo Sep 12, 2023, 10:58 AM

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2.0, 1.0, 4, 3

x = y;
````1.0, 1.0, 4, 3`

```cpp
y = x;
````1.0, 1.0, 4, 3`

```cpp
i = 2 * i;
````1.0, 1.0, 8, 3`

```cpp
j = 2 * j;
````1.0, 1.0, 8, 6`

woven sundial Sep 12, 2023, 10:58 AM

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yh

woven sundial Sep 12, 2023, 10:58 AM

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supple wraith can you click on the left of line numbers next to your file to put a red dot?

yh

woven sundial Sep 12, 2023, 10:59 AM

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ionic cargo `2.0, 1.0, 4, 3` ```cpp x = y; ````1.0, 1.0, 4, 3` ```cpp y = x; ````1.0, 1.0, ...

yh thats how i got 1 1 8 6

ionic cargo Sep 12, 2023, 10:59 AM

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yes but again

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the names are a different order

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the original has y, x, j, i in the call

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and only y and j are references in the function

supple wraith Sep 12, 2023, 10:59 AM

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woven sundial yh

great, those are breakpoints. now when your run your code using codeblocks, the execution will pause when it reaches a breakpoint, and you can inspect your variable's values before resuming

woven sundial Sep 12, 2023, 10:59 AM

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supple wraith great, those are breakpoints. now when your run your code using codeblocks, the ...

ok

supple wraith Sep 12, 2023, 11:00 AM

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debugging is INVALUABLE

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you need to learn to debug

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there is no way around it, you cannot be serious as a programmer if you don't learn how to use a debugger

woven sundial Sep 12, 2023, 11:00 AM

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supple wraith you need to learn to debug

ok i'll take note of that tysm

ionic cargo Sep 12, 2023, 11:00 AM

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compact marsh ```c++ Mystery(a, b, c, d) void Mystery(double e, double& f, double g, double& h...

@woven sundial this is very important tounderstand too. Functions arguments are positional not named

woven sundial Sep 12, 2023, 11:00 AM

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ionic cargo <@1102551347921944626> this is very important tounderstand too. Functions argume...

ok concerning this

ionic cargo Sep 12, 2023, 11:01 AM

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int foo(int a);

int b = 0;
foo(b);//positional, not named

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a is just the internal name for that parameter that foo uses

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all that anyone else cares about is the order of parameters

woven sundial Sep 12, 2023, 11:02 AM

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ok but in this part
void Mystery(double x, double& y, int i, int& j) {
x = y;
y = x;
i = 2i;
j = 2j;

}
when the values are passed isn't supposed to be x = 1.0, y = 1.0, i = 8, j = 6?

supple wraith Sep 12, 2023, 11:03 AM

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sorry to insist but you can actually see what happens and how if you just debug your code

ionic cargo Sep 12, 2023, 11:03 AM

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woven sundial ok but in this part void Mystery(double x, double& y, int i, int& j) { x = y...

idk what you mean

supple wraith Sep 12, 2023, 11:03 AM

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it's way simpler than asking strangers on the internet what your stuff does

ionic cargo Sep 12, 2023, 11:04 AM

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the internal values at the end of the call are 1 1 8 6

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but those don't map directly to x, y, i, j inside main

woven sundial Sep 12, 2023, 11:04 AM

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then

ionic cargo Sep 12, 2023, 11:07 AM

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it might get more clear if we use a b c d instead of using 2 sets of x y i j

int main() {
  // ...
  double a = 1.0;
  double b = 2.0;
  int c = 3;
  int d = 4;
  Mystery(b, a, d, c);
  // ...
}

void Mystery(double x, double& y, int i, int& j);

compact marsh Sep 12, 2023, 11:07 AM

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finally

ionic cargo Sep 12, 2023, 11:07 AM

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lol we did the same thing

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but yeah if it was that way you would get 1 1 6 8

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but its not

compact marsh Sep 12, 2023, 11:09 AM

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i added & to the other 2 btw it's not his code

ionic cargo Sep 12, 2023, 11:09 AM

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yeah I noticed

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thats why I said its no that

woven sundial Sep 12, 2023, 11:09 AM

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you get 1186 here?

ionic cargo Sep 12, 2023, 11:09 AM

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this is just going to be confusing

woven sundial Sep 12, 2023, 11:09 AM

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i cant understand

ionic cargo Sep 12, 2023, 11:09 AM

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having too many different versions of the code doesn't help

ionic cargo Sep 12, 2023, 11:10 AM

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ionic cargo it might get more clear if we use `a b c d` instead of using 2 sets of `x y i j`...

okay lets just go to my simple example

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its the same code

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but I renamed the variables inside main so we can differentiate them

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b -> x, a -> y, d -> i, c -> j

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then you go through and end up with the 1 1 8 6 like we had before

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buuuut

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only y and j are references

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so the only values inside main that actually change are the ones that were originally passed to those

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which are a and c

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now a was 1.0 anyway so its still 1.0. but c was 3 and now its 6

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b and d remain unchanged

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giving us 1 2 6 4

woven sundial Sep 12, 2023, 11:13 AM

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ahhhhhh

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ok

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yh

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i get it now

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yh

ionic cargo Sep 12, 2023, 11:14 AM

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also because its passed as Mystery(b, a, d, c) its even more confusing

woven sundial Sep 12, 2023, 11:14 AM

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man ty for being patient with me

ionic cargo Sep 12, 2023, 11:14 AM

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because you would expect them to go `Mystery(a, b, c, d)

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but its not

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so yeah

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keep an eye out for that stuff

woven sundial Sep 12, 2023, 11:15 AM

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tysm

ionic cargo Sep 12, 2023, 11:15 AM

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and remember that locals are local

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:D

woven sundial Sep 12, 2023, 11:16 AM

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!solved

#Can anybody help me with this code?