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[Bumber]

I can do if statements fine and I know how they work but for some reason I can't get my else if statements to plug in with the rest.

You've got a } in the wrong place. The } below "cin >> radiusC;" causes "if (menuOption == 1)" to end, meaning "if (radiusC < 0)" is outside. This means it's running no matter what your menu option, which means it's getting uninitialized garbage values if you didn't choose 1.

Edit: Ispil explains it better.

[Bauglir]

oh, oops, yeah, that's actually the cause of your immediate problem

[3man75]

You must use the operator ==, not =, for conditions.

= is the assignment operator. What's happening is that your code is that you get to the if statement, then it evaluates the condition you give it. The operator returns 1 because it succeeded, and C++ (at least if C is anything to go by) treats any nonzero value as True when you use it as a boolean (a boolean is a data type that can only have the values True or False). At least that's what I think the reason for that behavior is, but the thing I know is that you'll get wacky results with this typo.

== is the comparison operator, and it returns True if the two things you hand it are equal, and False otherwise.

You had it right the last time, so I don't know why you changed it.

This bit that you gave me:

Spoiler (click to show/hide)

if (userRequest == 1)
   {
      cout << "Hello user: Please input the radious of your circle. " << endl;
      cin >> radiousC;
      if(radiousC >= 0)
      //Above is needed for the submenu of the circle which takes radious and later checks it.
         {
         //in here is the actual forumula when the radious is inputed correctly.
         cout << "This is the area of your circle: " << endl << pow(radiousC, 2)*pie << endl;
         }
      else
         {
         cout << "Please input a positive number.";
         }
   }

or this one

Spoiler (click to show/hide)

#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;


int main(){

   double pie = 3.14;

   int radiousC = 0;

   int exponentC = 2;

   //--------------------------

   int lenghtR = 0;

   int widthR = 0;

   //--------------------------

   int baseT = 0;

   int heightT = 0;

   int userRequest = 0;




   cout << "Hello User. Please input a number corresponding to what you need." << endl << endl;

   cout << " 1. Circle Calculator." << endl;

   cout << " 2. Rectangle Calculator." << endl;

   cout << " 3. Triangle Calculator." << endl;

   cout << " 4. Quit application." << endl;

   cin >> userRequest;
   // Above is needed for the selection in the menu. Below is menu.




   if (userRequest == 1)
   {

      cout << "Hello user: Please input the radious of your circle. " << endl;

      cin >> radiousC;
      //Above is needed for the submenu of the circle which takes radious and later checks it.
   

         {
         //in here is the actual forumula when the radious is inputed correctly.
         cout << "This is the area of your circle: " << endl << pow(radiousC, 2)*pie << endl;

         }



   }

   if (userRequest == 2){

      //below it SHOULD be asking for information.
      cout << "Hello user: please input the lenght of your rectangle." << endl<< endl;

      cin >> lenghtR;

      cout << "Hello user: please input the width of your rectangle." << endl << endl;

      cin >> widthR;


   }

   system("Pause");

   return 0;

EDIT: Sorry clicked the glow thing by accident during a freeze on my pc.

[3man75]

Thanks. I'll be working on it so more tommorow. It's 12 o'clock and I need rest before I tackle this again.

[Dutrius]

Code: [Select]

public int Recursion()
{
    return Recursion();
}

Sorry, I just had to share that.

[Gatleos]

I was making a Game of Life program to practice programming in C for my operating systems class (where we're required to use C exclusively), and I decided to try and use an unbounded 2D plane instead of defining a size for it. My solution was to store the coordinates of all living cells rather than all the cell states in the defined area, so it doesn't matter how far they go (practically). But I just realized I have a problem.

Is there a C standard library equivalent of std::set? I prototyped my idea in C++ and it works fine, but unless there is an equivalent in C I guess I'll have to write my own... which also brings up the problem that I'll need to write my own hash-based comparison function for 2D coordinates. I've never quite figured out a way to do that.

I'm using the unix standard library.

[3man75]

Gatleos could you send me your code to try it out on my compiler? I'm interested in how a 'game of life' works. By the way what school do you go to that mandates using C only? I've heard that C++ was old but still taught as a way to help introduce Java later on. Is C still being used for research or some behind the scenes stuff?

[MagmaMcFry]

Gatleos could you send me your code to try it out on my compiler? I'm interested in how a 'game of life' works. By the way what school do you go to that mandates using C only? I've heard that C++ was old but still taught as a way to help introduce Java later on. Is C still being used for research or some behind the scenes stuff?

Conway's Game of Life is this, and here's a very good Life engine you can have a look at.

[Putnam]

IMO, Java and C++ are both just awful for learning programming. C++ because of the fairly long development pipeline compared to some simpler languages, Java because of all the damn boilerplate.

[i2amroy]

C is still commonly used in embedded systems work in the real world as well as tons of other lower level things (such as operating systems). (And for what it's worth, any C program will compile in C++ as well). C++ as is is still an excellent language to learn, currently being the 3rd most commonly used language (being beaten by plain old C and by Java, which has been in a slow and steady decline for years now).

Really the only "obsolete" languages you'll ever run into as a computer person are some of the ones that were developed back in like the 40's (and even some of those are still viable, having been updated tons since then).

[Reelya]

C++ is not used to help learn Java. That's almost certainly 100% reversed from the way things actually work. It's actually pretty hilarious to think anyone thinks that C++ is a beginners "learning" language as a stepping-stone to learning Java. In Lego terms, that would be like saying you bought a Lego Mindstorm Robotics kit as a way to help you learn how to use Duplo

C++ first could make sense, but in the learning-to-drive sense that learning on a manual means you can do both, whereas learning on an automatic transmission means you might get into lazy bad habits. But the reason isn't to ease-into automatic driving, the reason is so that you can use the manual transmission when needed. Race cars are manual transmission. C++ is the Formula One car of programming, superfast but hard to control.

Java: runs slow, but simple syntax, and works on interpreters on any machine, so you can deploy it via the web. It's used for stuff where you don't really care about performance.

C++: runs really fast, but much more knowledge required, and needs to be compiled separately for each target operating system. It's used for high-performance areas, such as games development and simulations.

[Putnam]

C is still commonly used in embedded systems work in the real world as well as tons of other lower level things (such as operating systems). (And for what it's worth, any C program will compile in C++ as well). C++ as is is still an excellent language to learn, currently being the 3rd most commonly used language (being beaten by plain old C and by Java, which has been in a slow and steady decline for years now).

Really the only "obsolete" languages you'll ever run into as a computer person are some of the ones that were developed back in like the 40's (and even some of those are still viable, having been updated tons since then).

I said it's awful to learn programming, not to learn.

[3man75]

Reelya if you could tell me what a Duplo is i'm doing it wrong? Dammit my proffesors lied to me!

Oh well. C++ to me is either really great once you can get to understanding it or a pain with all of its ultra precison in complicated synthax. I.E

cout <<
cin >>

I learned the signals by heart imagining a racecars going outside a tunnel or inside with those two. Not hard but when you add..

pow(x,y) where x and y can be heavilly modified and can have extra parenthesis.

Nesting If's has also been troublesome because I was given the logic to 'connect the if's like you would blocks' instead of stuffing them in together.

Previous believed this:

Block of if 1
--------------------separated but connected.
Block of if 2.

Instead of:

Block 1 (

Block 2()

)

Thanks for the racecar analogy on fast racecars i'll be sure to tell my friends tomorrow after class.

C is still commonly used in embedded systems work in the real world as well as tons of other lower level things (such as operating systems). (And for what it's worth, any C program will compile in C++ as well). C++ as is is still an excellent language to learn, currently being the 3rd most commonly used language (being beaten by plain old C and by Java, which has been in a slow and steady decline for years now).

Really the only "obsolete" languages you'll ever run into as a computer person are some of the ones that were developed back in like the 40's (and even some of those are still viable, having been updated tons since then).

I said it's awful to learn programming, not to learn.

To me it feels great and optimistic once you actually get the concepts but a pain to implement them not learn them.

[MagmaMcFry]

3man, I think you really aren't getting the concept of what a program is. It's just a list of instructions for a computer. If someone gave you a list of instructions, how would you do them? You'd do them one by one, starting from the top, then going to the bottom. Computers do just the same.

Now let's say there's an instruction that says "Is your number bigger than four? If yes, then do the instructions in these braces, but if no, then skip them". This is exactly what an if statement does. "If your number is bigger than four, then do the instructions in these braces, otherwise skip them".

[i2amroy]

Race cars are manual transmission. C++ is the Formula One car of programming, superfast but hard to control.

Probably not the best analogy anymore. Nowdays automatic transmissions have gotten so good that they are actually better than humans in most cases now, and as such it's now a 5/2 ratio... in favor of automatic/double transmissions. Technology marches on and all that jazz.

I said it's awful to learn programming, not to learn.

Sorry, my statement was more aimed at the "C++ is only good as a learning stone for Java" comment, not at your post. XD