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Thread Rules
1. This is not a "do my homework for me" thread. If you have specific questions, ask, but don't post an assignment or homework problem and expect an exact solution.
2. No recruiting for your cockamamie projects (you won't replace facebook with 3 dudes you found on the internet and $20)
3. If you can't articulate why a language is bad, don't start slinging shit about it. Just remember that nothing is worse than making CSS IE6 compatible.
4. Use [code] tags to format code blocks. |
On November 09 2011 11:05 dapierow wrote:
Im having some trouble with array lists and abstract classes in java
im trying to create a method called "add" in my "collection" class for adding an abstract class into an array list, and I have a different class as a test class, the test class will add a subclass of the abstract class but i cannot seem to make the add method work in the "collection" class... I either get an error of cannot use an abstract class or an error of it being pointed to null...
post code, no one can follow that explanation x)
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On November 09 2011 18:53 MisterD wrote:Show nested quote +On November 09 2011 11:05 dapierow wrote:
Im having some trouble with array lists and abstract classes in java
im trying to create a method called "add" in my "collection" class for adding an abstract class into an array list, and I have a different class as a test class, the test class will add a subclass of the abstract class but i cannot seem to make the add method work in the "collection" class... I either get an error of cannot use an abstract class or an error of it being pointed to null... post code, no one can follow that explanation x)
You can't really do anything with abstract classes can you? Don't they need to actually be instantiated before you can use them?
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On November 10 2011 07:13 Millitron wrote:Show nested quote +On November 09 2011 18:53 MisterD wrote:On November 09 2011 11:05 dapierow wrote:
Im having some trouble with array lists and abstract classes in java
im trying to create a method called "add" in my "collection" class for adding an abstract class into an array list, and I have a different class as a test class, the test class will add a subclass of the abstract class but i cannot seem to make the add method work in the "collection" class... I either get an error of cannot use an abstract class or an error of it being pointed to null... post code, no one can follow that explanation x) You can't really do anything with abstract classes can you? Don't they need to actually be instantiated before you can use them?
You can't use them directly but I think his intent is use have a collection of objects that inherit the abstract class. So yeah, he probably needs to create some subclasses of that abstract.
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On November 10 2011 07:31 omgbnetsux wrote:Show nested quote +On November 10 2011 07:13 Millitron wrote:On November 09 2011 18:53 MisterD wrote:On November 09 2011 11:05 dapierow wrote:
Im having some trouble with array lists and abstract classes in java
im trying to create a method called "add" in my "collection" class for adding an abstract class into an array list, and I have a different class as a test class, the test class will add a subclass of the abstract class but i cannot seem to make the add method work in the "collection" class... I either get an error of cannot use an abstract class or an error of it being pointed to null... post code, no one can follow that explanation x) You can't really do anything with abstract classes can you? Don't they need to actually be instantiated before you can use them? You can't use them directly but I think his intent is use have a collection of objects that inherit the abstract class. So yeah, he probably needs to create some subclasses of that abstract.
I figured out my question
I did have the subclasses created but since, the sub class is figured out by my test code I had to use the abstract class
my problem was I tried to get the information i needed for my "add" method from an initialized object of the class, rather than the getter from the abstract class (which i totally forgot about).  Problemo solved
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hi guys! I need some help with a problem in c programming :\
so I need to ask the user to input a single character (one of the following: "r", "b" or "p") using scanf. however the problem is to actually check if the inputted data is actually "r, b or p". I wanted to use a while loop to check the input: if it is the correct values, it returns a value back to the main program. otherwise, the loop repeats until the input is correct. Or something like that. I'm familiar with checking input for numbers, but for characters? by the gods I need some help.
char pq;
printf("Enter quality (p: premium, r: regular, b: basic):");
scanf(" %c",&pq);
while (pq != 'r' || 'b' || 'p'){
printf("###Error! Quality must be p, r or b!\n");
printf("Enter quality (p: premium, r: regular, b: basic):");
scanf(" %c",&pq);
}
return pq;
and I can't seem to get the results :\ maybe I'm missing something in the logic tests?
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On November 10 2011 13:30 MiyaviTeddy wrote:
hi guys! I need some help with a problem in c programming :\
so I need to ask the user to input a single character (one of the following: "r", "b" or "p") using scanf. however the problem is to actually check if the inputted data is actually "r, b or p". I wanted to use a while loop to check the input: if it is the correct values, it returns a value back to the main program. otherwise, the loop repeats until the input is correct. Or something like that. I'm familiar with checking input for numbers, but for characters? by the gods I need some help.
char pq;
printf("Enter quality (p: premium, r: regular, b: basic):");
scanf(" %c",&pq);
while (pq != 'r' || 'b' || 'p'){
printf("###Error! Quality must be p, r or b!\n");
printf("Enter quality (p: premium, r: regular, b: basic):");
scanf(" %c",&pq);
}
return pq;
and I can't seem to get the results :\ maybe I'm missing something in the logic tests?
I would bet that your problem is here:
while (pq != 'r' || 'b' || 'p')
Have you tried splitting it up, so its something like
while (pq != 'r' || pq != 'b' || pq != 'p')
If that doesn't work, try splitting it up further with parenthesis between the statements.
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Like Millitron said, you need to write the pq != _ for each character, else it will be interpreted as while ((pq != 'r') || 'b' || 'p' ) which will always be true as 'b' and 'p' count as true in boolean expressions in C. Furthermore, you want to use logical AND rather than OR in this case, ie while(pq != 'r' && pq != 'b' && pq != 'p').
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by the gods it works.
Thanks alot Milli & Ink! I actually understood where it went wrong with the logical Or.
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What is your craziest terminal outfit?
Earlier today I had an xmonad workspace with a split layout. On one window was a screen running vim with multiple windows, on the other was another split vim instance inside screen and through ssh. When it came time to switch from one vim to the other (yank & paste), I had to do one keystroke for xmonad, another for screen (vim wasn't the active screen), and another for the correct vim window. Strangely enough I didn't blink and scratch my head until after I had already completed the operation.
I suppose it could have been worse.
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United States1176 Posts
On November 10 2011 18:18 mmp wrote:
What is your craziest terminal outfit?
Earlier today I had an xmonad workspace with a split layout. On one window was a screen running vim with multiple windows, on the other was another split vim instance inside screen and through ssh. When it came time to switch from one vim to the other (yank & paste), I had to do one keystroke for xmonad, another for screen (vim wasn't the active screen), and another for the correct vim window. Strangely enough I didn't blink and scratch my head until after I had already completed the operation.
I suppose it could have been worse.
<3 xmonad. =D
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Need some help with dereferencing here...
I would like to create a input manipulator with parameters which is similiar to getline function. However, how it will work is the following
cin >> getFileName(input);
where getFileName() is the manipulator and input is an empty c-string that will be passed in and filled with data.
What I did was to create a class with the following prototype:
+ Show Spoiler +
class getFileName {
public:
getFileName(char*);
friend istream& operator>>(istream&, getFileName);
private:
char** inputPtr;
};
getFileName::getFileName(char* input)
{
inputPtr = &input;
}
istream& operator>>(istream& is , getFileName file)
{
cout << *(file.inputPtr) << endl;
return is;
}
int main()
{
char input[50] = "ABC";
cin >> getFileName(input);
The problem is when I call the manipulator, when it gets to the overloading of >> method, it will display garbage when I dereference the char**, despite me passing in a cstring with content. I tried making a char* attribute in getFileName class and let inputPtr point towards it and it will work when dereferencing. So any ideas on where could have gone wrong?
Note: Tried testing on which address inputPtr points to in the constructor and in the operator>> overload and they both point to the same address, yet when dereferenced, 1 gives the content and the other gives garbage.
Edit: Solved the problem by changing all char* type to string type, and passing arguments in constructor by reference.
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Please
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forum
tag
for
verbatim
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So here is the deal,
im trying to learn c++ for over a year now. I never put much time into it , but recently i managed to create some console applications like snake,hangman,rock paper scissors, and a calculator with a LOT of cool functions. Im getting used to using classes, functions, arrays,loops and all the other basic stuff.
Now i want to go further, but i dont really know how. What would be the next step to learn right now?
My Idea was to create a program which is able to create lists of video files (series,movies) , sort them by different attributes ,like seasons, names , whatever and display them in the main form. Maybe make it be able to let the user chose the path to different folders. It would also be really cool if it could pick a random videofile and play it in a mediaplayer.
Will i be able to realize this with my current knowledge? Is there anything i should go into before this? I guess i should look up how file access works as the next step??
Up to this point ive only been using dev-c++ as compiler. I recently downloaded Virtual c++ , because i wanted to do this with a GUI. Just played a little bit with the toolbox , did nothing else with vc++ so far. It looks really confusing.
So basically im asking for general advices, tips, keywords to search on google to go on.
Or maybe a better idea, what i could do next.
sorry for my bad english.
Greez, Tkorpe
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I figure a good amount of people might be interested in picking up the C language as a beginning programmer, and be interested in learning to code their own game. I'm writing a series of articles on how to create a game through Windows Console, and though it'd be a cool thing to throw up in this thread as well, maybe even include it somewhere in the OP perhaps?
TL Blog about the series of articles.
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use Qt for GUI
its a nice and easy to use GUI library
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In Visual Studio 2010 (C#), is there a way to automatically increment the Version property and ProductCode property of a deployment project when it's built, such that the Version property becomes the AssemblyFileVersion from the project it's using to build the .exe/.msi?
As in, if my project updates to e.g. 1.05.1234 and then I build the installer project, it will in turn update to 1.05.1234 and also update the ProductCode.
I feel this should be a simple task involving the build events, but I can't figure it out.
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Hi, I am having trouble initializing variables using str.at(). in c++
for example,
if I have a code like
cin >> str;
b = (str.at(0));
c = (str.at(1));
when imputting a string such as 12, it wont initialize properly, and it will instead give me something like
b = 50
c = 58
I don't know why its not initializing properly 
Thanks
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where does business logic go in an mvvm pattern?
should the viewmodel contain any business logic?
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On November 18 2011 13:06 Frosticles wrote:Hi, I am having trouble initializing variables using str.at(). in c++ for example, if I have a code like cin >> str; b = (str.at(0)); c = (str.at(1)); when imputting a string such as 12, it wont initialize properly, and it will instead give me something like b = 50 c = 58 I don't know why its not initializing properly Thanks
make sure b and c are a string or char
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EPT
