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[Skyrunner]

I can't think of many applications where XML would be strictly better than JSON. The ease of use and parsing for JSON is just so good, PLUS it has a looot less boilerplate for simple data.

[LoSboccacc]

look at the little nerdy car go

http://rednuht.org/genetic_cars_2/

this need to become  game, somehow

I had best result with 30% / 30%

[Orange Wizard]

That's pretty awesome.

[3man75]

Got a problem with a small question. It's asking me to print two strings in alphabetical order. I can get the following resulets:

 [Imagine a checkmark here] Testing input rabbits capes
Your output:  capes rabbits
✖   Testing input capes rabbits
Expected output:  capes rabbits
Your output:  rabbits capes
 Tests aborted.

by inputting this piece of code: cout << secondString << " " << firstString << endl;

I'm confused why my code goes from capes rabbits to rabbits capes when they change the input. I don't know how to proceed from here.

Spoiler (click to show/hide)

#include <iostream>


Print the two strings in alphabetical order. Assume the strings are lowercase. End with newline. Sample output:
capes rabbits



#include <string>
using namespace std;

int main() {
   string firstString;
   string secondString;

   firstString = "rabbits";
   secondString = "capes";

   cout << secondString << " " << firstString << endl;
 
 
   return 0;
}

[Bauglir]

How are they even giving input? You've written a main function that appears hard coded to print two particular strings in a particular order - no sorting at all. It sounds like they want you to write a function that takes an arbitrary pair of strings as arguments, and then prints them in the correct order.

[Orange Wizard]

Surely C++ has a generic sorting function that could be used?

[Reelya]

well no, you can use the stl::sort functionality, but this assignment is clearly about how to write the sorting code so that you learn about string handling. If everyone just learned by using black-box library functions we end up running out of people who are smart enough to actually write the underlying code. C++ is for writing underlying code, and knowing how to do that in the minimal amount of memory or fastest possible time, not quick hacks that just get the job done without you needing to know what's going on.

EDIT: btw STL is pretty powerful, but if you start doing sizeof checks you realize that they're all hideously bloated memory hogs compared to writing your own light-weight classes. An empty STL string takes 28 bytes of pure bloat. You can get that down to maybe 4-8 bytes by writing your own light-weight wrapper around a char* and a "int size". With just that, you can implement most of the stuff from std::string that's actually useful.

3man75: your code seems to be just swapping the position of the strings, it's not sorting them alphabetically. You have to sort them into correct order, no matter what order they come in the input.

[Orange Wizard]

well no, you can use the stl::sort functionality, but this assignment is clearly about how to write the sorting code so that you learn about string handling. If everyone just learned by using black-box library functions we end up running out of people who are smart enough to actually write the underlying code. C++ is for writing underlying code, and knowing how to do that in the minimal amount of memory or fastest possible time, not quick hacks that just get the job done without you needing to know what's going on.

Right, that makes sense. I use Python too much.

[i2amroy]

Ah Python, the language that will keep the C/C++ programmers who write all of the actual fast libraries for it employed for years to come.

[3man75]

well no, you can use the stl::sort functionality, but this assignment is clearly about how to split strings up and write sorting code. Sure, he could grab some premade libraries that already do everything, but that would sort of defeat the purpose of learning how to write the underlying code. C++ is for optimized low-level programming such as games. And you're an idiot if your final version of a game is riddled with STL calls.

STL is pretty powerful, but if you start doing sizeof checks you realize that they're all hideously bloated memory hogs compared to writing your own light-weight classes.

3man75: your code seems to be just swapping the position of the strings, it's not sorting them alphabetically. You have to sort them into correct order, no matter what order they come in the input.

How do you sort? I'm a little lost when you guys talked about this because I've never seen anything that involves sorting in the chapter.

[Reelya]

To sort something, you need two basic bits of code:

- a method to compare two values
- a method to swap two values

then, with only two inputs, you only need to do two things:

- check if the first value is higher than the second value
- if the check was true, swap the values

So you need to find or create a string comparison function. to do that you need to go through letter by letter until you find one that's lower alphabetically than the other. The basic outline is like this:

Spoiler (click to show/hide)

Code: [Select]

bool isGreaterThan(string string1, string string2) // returns TRUE if string1 > string2 in alphabet
{
   int length = min(string1.length, string2.length); // find minimum of both strings length

   for(int i = 0; i < length; i++)
   {
       if(string1[i] < string2[i])
          return false; // string2 was greater
       else if(string1[i] > string2[i])
          return true; // string1 was greater
   }
   // if the loop exited, then the strings matched completely up to the minimum length of both strings, e.g. "cat" vs "cattle"

   // one rule that can be applied is that the shorter string comes first. e.g. "cat" would come before "cattle"
  // i.e if string1 is longer, we return "true" for "isGreaterThan":

   if(string1.length > string2.length)
     return true;

   // but in all other cases now, we return false, because either string2 is greater or they're both the same - meaning string1 is not greater-than string2
   return false;
}

Once you have a working comparison function you need to sometimes swap two strings so that they are in the right order. and you swap two things by making a "temp" variable, then backing up one of the values in that:

Spoiler (click to show/hide)

if( isGreaterThan(string1, string2) )
{
    string temp = string1;
    string1 = string2;
    string2 = temp;
}

[Bauglir]

Given the setup, they're probably easing you into the idea of sorting, which may be why they haven't used the word. You don't need to do a full-blown sort (that is, you don't need to swap anything). All you need to do is compare the strings until you can determine which to print first.

In this case, you will need to define a string comparison like Reelya just said, then something like

Code: [Select]

if isGreaterThan
    print String2, then String1
else
    print String1, then String2
What I just wrote is what's called pseudocode, if that's not a concept you're familiar with. I laid out a vague structure, but since I'm not really familiar with C++ syntax I didn't bother writing the correct version.

What Reelya suggested or what I just did should both work, it's just a matter of what you're more comfortable with and what you think your class expects.

[Uristides]

look at the little nerdy car go

http://rednuht.org/genetic_cars_2/

this need to become  game, somehow

I had best result with 30% / 30%

Oh my god it's just like boxcar2d but with even more pretty graphs to look at. Shame it's only 2 wheels max.

[Reelya]

We have a thread about this game already:
http://www.bay12forums.com/smf/index.php?topic=152831

[Magnumcannon]

I'm trying to do some kind of questionnaire or something in Python 2.7 that will display the user's answers at the end. I'm not even done with it but i encountered some problems with loops.

Spoiler (click to show/hide)

print "What's your name?"
name = raw_input ('>')
while True:
    print "How old are you, %s?" %name
    age = raw_input ('>')
    if age <= 122:
        break
    else:
        print "This doesn't seem right."       
   
print "Sandwich!"

Everytime i reach the first loop, it doesn't break. Ever. Like, it will keep asking the age even if the age is valid. I tried adding a variable before the loop, making it something like this.

Spoiler (click to show/hide)

print "What's your name?"
name = raw_input ('>')
a = True
while a == True:
    print "How old are you, %s?" %name
    age = raw_input ('>')
    if age <= 122:
        a = False
    else:
        print "This doesn't seem right."       
   
print "Sandwich!"

It didn't work either. It just keeps looping forever. I know this is likely a very basic problem, so basic i can't find an answer online. My objective is to get that "Sandwich" printed, so i know the loop is dead and i can insert the next question.