Need help finding the radius of my circle..

[MJGilbert]

Hi guys, I have been looking around the forum for a little while and I love this place. I can't seem to find my answer though so I decided to make my own post.
Details:
-I am using x code
-I am trying to find the distance between 2 points
-I keep getting "Non-ASCII characters are allowed outside of literals and identifiers (I will point out where)
-There is one more thing I will point out

  #include <cmath>
#include <iostream>

using namespace std;

int main()
{
    float mpx;
    float mpy;
    int x1;
    int y1;
    int x2;
    int y2;
    int cpx;
    int cpy;
    int radius;
    srand(time(0));
    rand();
    
    cout << "Please enter the location of your circle\'s midpoint." << endl <<endl;
    cout << "Enter the x coordinate of your circle\'s midpoint (-99 to 99): ";
    cin >> mpx;
    cout << "Enter the y coordinate of your circle\'s midpoint (-99 to 99): ";
    cin >> mpy;
    cout << endl;
    
    x1 = rand() % 199 - 99;
    y1 = rand() % 199 - 99;
    x2 = rand() % 199 - 99;
    y2 = rand() % 199 - 99; /*This random always goes above and beyond 199 - 99
 and it is killing me, I just cannot figure out why!*/
    
    cout << "The location of a point on your circle\'s ciricumference has been randomly set to: ";
    //Displays first x coordinate
    cout << "\nx1 coordinate: " <<x1;
    //Displays first y coordinate
    cout << "\ny1 coordinate: " <<y1;
    //Displays second x coordiante
    cout << "\nx2 coordinate: " <<x2;
    //Displays second y coordinate
    cout << "\ny2 coordinate: " <<y2;
    //Displays the length of the circle's radius using √((p0x – p1x)2 + (p0y – p1y)2)

    cout << "The length of the radius of the circle is " << sqrt((x1 – x2)*2) + (y1 – y2)*2)) /* 
This is where I keep getting my problem... 
In xcode, it keeps saying (and pointing to)
 Non-ASCII characters are not allowed outside of literals and identifiers. 
It points to the 2 on the end of the parenthesis.
It also says "character expected" and shows a close parenthesis. 

    //Displays the circle's area using
    cout << "The area of the circle with a radius of # is #" <<endl;
    
    return EXIT_SUCCESS;
    
}
 */

Thanks in advance guys, I appreciate it!

[cire]

You have mismatched parentheses on line 44 and your – on the same line is not an ascii character.

[keskiverto]

Besides, you want the square of the difference, not "times two".

[MJGilbert]

Thanks guys, how would i use pow()? I get an error for that too... I also tried ^2. Sorry for the noob questions... I put || instead of the minus because -- gives me an error as well! Isn't that for boolean though?

Thanks again

[eyenrique]

I have an example using pow function,
hope this help:

//pow.cpp
//Use pow function.

#include <iostream>
using std::cout;
using std::cin;
using std::endl;

#include <cmath>
using std::pow;

int main(){

double number;

cout<<"Enter a number: ";
cin>>number;

cout<<number<<"^2 is: "<<pow(number,2)<<endl;

return 0; //indicates success
}//end main 

Eyenrique-MacBook-Pro:Help Eyenrique$ ./pow 
Enter a number: 3
3^2 is: 9
Eyenrique-MacBook-Pro:Help Eyenrique$ ./pow 
Enter a number: 4
4^2 is: 16
Eyenrique-MacBook-Pro:Help Eyenrique$ ./pow 
Enter a number: 2
2^2 is: 4

You have to use double type variables.

[Chervil]

You could do either
(x1 - x2)*(x1 - x2)
or
pow((x1 - x2), 2.0)

The ^ operator is something else entirely, its one of the bitwise operators, used for manipulating integers at the bit level.

I put || instead of the minus because -- gives me an error as well!

You need to use - for minus. I suspect you are having problems due to using a word processor for editing code (well, I'm guessing here). You need to use either a plain text editor (notepad etc) or a proper code editor.

[Disch]

Please do not use pow() to square stuff.

Talk about using a sledgehammer to swat a fly.

[eyenrique]

poor fly Dx
by the way thanks for advice @Disch

[MJGilbert]

Talk about using a sledgehammer to swat a fly.

LOL... So I should use

(x1 - x2)*(x1 - x2)

?

You need to use - for minus. I suspect you are having problems due to using a word processor for editing code (well, I'm guessing here). You need to use either a plain text editor (notepad etc) or a proper code editor.

I am doing everything directly within xcode.. I just don't understand why

-

won't work... Do you think it is because I tried to power wrong?

[MJGilbert]

    cout << "The location of a point on your circle\'s ciricumference has been randomly set to: ";
    //Displays first x and y coordinates
    cout << "\n(" <<x1 << ", " << y1 << ")";
    //Displays second x and y coordinates
    cout << "\n(" <<x2 << ", " << y2 << ")" <<endl;
    //Displays the length of the circle's radius using √((p0x – p1x)2 + (p0y – p1y)2) divided by 2
    cout << "\nThe length of the radius of the circle is " << sqrt((x2 - x1)*(x2 - x1)) + ((y2 - y1)*(y2 - y1)) << endl;
    //Displays the circle's area using
    cout << "\nThe area of the circle with a radius of # is #" <<endl;
    
    return EXIT_SUCCESS;
    
}

Ended up with this

Please enter the location of your circle's midpoint.

Enter the x coordinate of your circle's midpoint (-99 to 99): 1
Enter the y coordinate of your circle's midpoint (-99 to 99): 1

The location of a point on your circle's ciricumference has been randomly set to: 
(54, -2)
(11, -43)

The length of the radius of the circle is 1724

The area of the circle with a radius of # is #
Program ended with exit code: 0

The radius just seem erroneous..

[Chervil]

The original code (displayed on this forum) contains a unicode character
UTF-8: E2 80 93
which is named "en dash"
This character doesn't normally appear on the keyboard, but it may be auto-generated by some editors. (such editors are unsuitable for writing code).

[MJGilbert]

I actually got it to work! Thanks, my only problem left is the number I end up with.. Is sqrt((x2 - x1)*(x2 - x1)) + ((y2 - y1)*(y2 - y1)) really giving me a true answer? Or am I not truly getting the answer I am looking for? Because the number I get is outrageous!

Thanks

EDIT: I tried pow() and it worked... Curious why the other way around didn't though. Thanks a ton guys! :)

[keskiverto]

Well, lets look at the sqrt((x2 - x1)*(x2 - x1)) + ((y2 - y1)*(y2 - y1))

Add some syntactic sugar:

dx = (x2 - x1)
dy = (y2 - y1)
// replace in equation:
sqrt( dx*dx )            + (dy*dy)
// which is logically same as:
abs(dx) + dy*dy

cire did already mention the mismatching parentheses of the OP version. I bet you did fix them in one way for multiplication and the other way for pow().

At least some editors can conveniently show, which parentheses do match.

[Chervil]

Or am I not truly getting the answer I am looking for? Because the number I get is outrageous!

The radius is the distance between the centre (mpx, mpy) and a point (x, y) on the circumference.

However, you seem to be calculating the distance between two different points and ignoring the centre. I don't know whether that affects your expected result, or if I misunderstood what you are aiming to achieve.