Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Mesa]

Kinda giving Python another shot over at Codecademy, a bit under halfway into the course so far.
It's much more fun than C++ or JavaScript (especially the former), barring the for+list+dict nonsense I had to slog through because I'm a dumbo when it comes to syntax apparently. :r

I wrote this kind of pointless 4-digit (pseudo)random number generator but it's mine goddamnit and it works. Plus there's the placebo effect making me think it's better than random's default randint generation in some weird way.

Code: [Select]

from random import randint


# Random seed generator of some sort
# The 4 digits of the seed, integers in the range of 0 (1 for the 1st) to 9
# They're generated as strings so they can be concatenated
def random():
        rng1 = str(randint(1,9))
        rng2 = str(randint(0,9))
        rng3 = str(randint(0,9))       
        rng4 = str(randint(0,9))       
        # The digits are concatenaded and converted to an int to create the seed
        seed = rng1+rng2+rng3+rng4
        seed = int(seed)
        return seed

[TheBiggerFish]

Uh, they shouldn't be? The generator should only need to know the location of a block, to decide if it should be air or stone.

Well.  Air or not-air.

[EnigmaticHat]

I have a question.  So I have a hex grid in C# (the fact that its a hex grid is irrelevant) which is recorded in a 1-dimensional array because simplicity.  I have a function that takes an x and y coordinate and returns the correct hex.

What I would *like* to do is be able to enter an invalid coordinate (as in, a negative number or something outside the grid) and have it return false.  I'm used to python where I can just return any old thing, but this is clearly not the case in C#.  So... how do you do that, or something functionally similar?

Code: [Select]

        public Hex getHex (int x, int y)
        {
            int num = 0;
            num += y * gridWidth;
            num += x;
            return grid[num];
        }

[itisnotlogical]

1) If the coordinates are invalid, return null or a special "Invalid hex" object and the caller is responsible for checking that.

2) Crash, and be careful when and how you use the GetHex function.

EDIT:

I've got it so that my function produces unconnected open rectangles. How does this idea sound for connecting them? It's a bit late and I'd like to sleep, so I'll take a crack at actually putting this in tomorrow.

Spoiler (click to show/hide)

- Find any two open spaces. Pick one to be “A” and one to be “B”, and start digging at A.

- If B is higher than A, dig upward until that is not the case. If B is lower than A, dig downward until that is not the case.

- If B is left of A, dig left until that is not the case. If B is right of A, dig right until that is not the case.

- While the above is happening, check that it's not digging into a room. Allow it to dig over ONE already-open space, for corridor intersections.

- If there are any unconnected rooms after n completely random attempts, deliberately pick a square in the space with a smaller area and make it connect to the larger one.

[Reelya]

@EnigmaHat: what he said, return a null then check for that. That works in C# since all object variables are references and null references are allowed. In C++ you'd need to either make a static "invalid" Hex which you return and return a reference to that, or use pointers and return null.

Another issue is that sometimes invalid x and y will return a (wrong) valid hex, e.g. if "x" is out of bounds, then it could return a Hex from a different y-column without crashing, whereas y out of bounds will push the array right out of bounds (unless paired with an invalud "x" that pushes it back into bounds). For example, if your x and y bounds are 10, then valid x and y are 0 to 9 in each dimension, with Hexes 0 to 99. The formula is "num = 10y + x". If y = 5 and x = -1 then you get num=49, which is the last cell of column 4. if y=-1 and x > 9, then this will also give a valid cell, even though both x and y on their own should be invalid.

So, definitely check that both x and y are valid individually before computing "num'.

Another option is to use assert statements (c# or c++) and write your code so that it never triggers the assert. Then, for your release build you can disable the assert's and get more performance than the version with manual bounds checking.

[Rose]

Another way you can do it, which I use sometimes, is have a function in the form of:

bool GetHex(int x, int y, out Hex hex)
{
    Stuff
}

Then you return true if it's a valid hex, and false if it's not, and the hex is returned through the 'out Hex hex' parameter.

But in your case, just returning null for an invalid hex should be fine.

[3man75]

My teacher just mailed me new homework (Frustrating. Yet this is still better than Uni i'm told) and it's asking about vectors. Which I understand to be similar to arrays.

The question goes something like this:
Resize vector countDown to have newSize elements. Populate the vector with integers {newSize, newSize - 1, ..., 1}. Ex: If newSize = 3, then countDown = {3, 2, 1}, and the sample program outputs:
3 2 1 Go!

She also gives a sample program that can somewhat be edited.


#include <iostream>
#include <vector>
using namespace std;

int main() {
   vector<int> countDown(0);
   int newSize = 0;
   int i = 0;

   newSize = 3;

  /* Solution goes here*/

   for (i = 0; i < newSize; ++i) {
      cout << countDown.at(i) << " ";
   }
   cout << "Go!" << endl;

   return 0;
}

((Bolded means it can't be edited. You can however make as many whitespaces as possible and declare new variables and of course input new things.))

My questions are basically this:
1. How do you use a Vector and what does it do?
2. If you know a bit of synthax and what it does please post that because it'll be uber helpful.
3. Just as a hint can I solve this by inputting a for loop and an if statement?

[miauw62]

Look up vector on cplusplus.com

I could explain this but I feel it'd be more useful for you to find out how 2 datastructures yourself.

[itisnotlogical]

I made my generator dig out corridors to connect any empty spaces.

Spoiler (click to show/hide)

For the first time in a long, long time, I've programmed something that I am genuinely proud of.

It still occasionally generates unconnected empty squares, and will often place the player inside of those. Fixing that is next on my to-do list. I'm debating whether I should force them to connect to the main branch, or fill them in with solid tiles so it's like they never existed. Or maybe even include a digging mechanic, so I can fill those unconnected spaces with goodies that the player can dig towards.

[EnigmaticHat]

1) If the coordinates are invalid, return null or a special "Invalid hex" object and the caller is responsible for checking that.

Thanks (and to everyone else who answered), that's what I was looking for.

[Bumber]

Trying to create a simple FTP program in Python. I've commented out code that I don't think is necessary. (I'm working under the assumption that sockets are full duplex, but I could be wrong.) The frustrating thing is that you can't simply send strings through the socket in Python3 as you can in Python2. I think you might have to convert them into bytearrays, but there's something about needing to set encoding (i.e., utf8, etc.) and I don't know how to specify that. File objects work. I don't know what the guarantees are about delivery; re-sending the hello might be unnecessary once it's confirmed to be in the socket.

I've detailed my intended protocol below. You can ignore the commands, I just want a working hello and goodbye on my control channel:

Spoiler: Protocol (click to show/hide)

Code: [Select]

python3 serv.py 1234
python3 cli.py localhost 1234

Control Channel
    Client -> Server
        hello (keep trying?)
            get <file> ================> port ==> close
            put <file>, numBytes, overwrite => port ===========> close
            ls ====> port ===> close
            quit ========> terminate
    Server -> Client
        ready
            get: numBytes/error(negative) => begin => close+ready
            put: ok/error (-1 already exist, 0 ok) => begin => close => ready
                (if already exists, 2nd req w/overwrite)
            ls:  ok ===> begin =====> close+ready
            quit: goodbye+terminate
    size/format
        Single byte: '\x##'
            01 = hello/ready
            02 = quit/goodbye
            03 = port (follow with len + separator + port_info)
            04 = begin
            05 = close
            10 = get/ok (follow with len + separator + parameter/return_msg)
            11 = put/ok (follow with len + separator + parameter/return_msg)
            12 = ls/ok  (follow with len + separator + parameter/return_msg)
            FF = separator

Data Channel
    Just bytes, no encryption

Use case:
    C01 -> S01 -> C10|6|FF|"a.txt\0" -> S10|len(int)|FF|100 -> C03|len(port_info)|FF|port_info -> S04 ->
        -> (S to C: 100 bytes via data channel) -> C05 -> S05 -> S01
    C11|len()|FF|("a.txt\0", 150, False) -> S11|len(int)|FF|-1 -> S01 -> C11|len()|FF|("a.txt", 150, True) ->
        -> S11|len(int)|FF|0 -> C03|len(port_info)|FF|port_info -> S04 -> (C to S: 150 bytes via data channel) ->
        -> S05 -> C05 -> S01
    C12|6|FF|"ls -l\0" -> S12|len(int)|FF|len(msg) -> C03|len(port_info)|FF|port_info -> S04 ->
        (S to C: len(msg) bytes via data channel; e.g., msg = "a.txt 150 bytes\n\0") -> C05 -> S05 -> S01
    C02 -> S02


Spoiler: Client Code (click to show/hide)

Code: (cli.py) [Select]

from socket import *
import os, sys, time

#CLIENT_LISTEN_PORT = 1235 #Port number of control channel to listen on. This should be the same as in serv.py
CONNECTION_SLEEP_TIME = 5 #Seconds to wait before retrying recv on failure

def recvAll(sock, numBytes):
recvBuff = "" #The buffer
tmpBuff = "" #The temporary buffer

while len(recvBuff) < numBytes: #Keep receiving until all is received
tmpBuff = sock.recv(numBytes) #Attempt to receive bytes
if not tmpBuff: #The other side has closed the socket
break
recvBuff += tmpBuff #Add the received bytes to the buffer

return recvBuff

def main():
if len(sys.argv) < 3: #Command line checks
print("USAGE python " + sys.argv[0] + " <Server Address> <Server Port>")

serverAddr = sys.argv[1] #URL or IP of server
serverPort = int(sys.argv[2]) #Port number of control channel
#global CLIENT_LISTEN_PORT #Port number of control channel to listen on
#global CONNECTION_SLEEP_TIME #Seconds to wait before retrying recv on failure

#listenSock = socket(AF_INET, SOCK_STREAM) #Create a TCP control socket for receiving
#listenSock.bind(('', CLIENT_LISTEN_PORT)) #Bind the socket to the listening port
#listenSock.listen(1) #Start listening for incomming connections
connSock = socket(AF_INET, SOCK_STREAM) #Create a TCP control socket for sending and receiving
connSock.connect((serverAddr, serverPort)) #Connect to the server
print("Attempting to connect to server..", end='')
temp = '\x00'
while temp != '\x01': #Keep sending 'hello' until we receive one
print('.', end='') #Add a dot each time we have to resend
connSock.send('\x01') #Say 'hello'
temp = connSock.recv(1) #Listen for 'hello'
if temp != '\x01':
print("Fail") #test string
time.sleep(CONNECTION_SLEEP_TIME) #Wait a bit before retry
temp = connSock.recv(1) #Last chance before resend
print("\nConnection established.")
cmd = input("FTP> ")

#Stuff goes here

while connSock.send('\x02') < 1: #Ready to quit
continue
while conSock.recv(1) != '\x02': #Wait for server to terminate
continue
connSock.close()
print("Connection terminated.")

main() #Start the program


Spoiler: Server Code (click to show/hide)

Code: (serv.py) [Select]

from socket import *
import os, sys, time

#CLIENT_LISTEN_PORT = 1235 #Port number of control channel to listen on. This should be the same as in cli.py
CONNECTION_SLEEP_TIME = 5 #Seconds to wait before retrying recv on failure

def recvAll(sock, numBytes):
recvBuff = "" #The buffer
tmpBuff = "" #The temporary buffer

while len(recvBuff) < numBytes: #Keep receiving until all is received
tmpBuff = sock.recv(numBytes) #Attempt to receive bytes
if not tmpBuff: #The other side has closed the socket
break
recvBuff += tmpBuff #Add the received bytes to the buffer

return recvBuff

def main():
if len(sys.argv) < 2: #Command line checks
print("USAGE python " + sys.argv[0] + " <Port>")

serverPort = int(sys.argv[1]) #Port number of control channel
#global CLIENT_LISTEN_PORT #Port number of control channel to send on
#global CONNECTION_SLEEP_TIME #Seconds to wait before retrying recv on failure

serverSock = socket(AF_INET, SOCK_STREAM) #Create a TCP control socket for sending and receiving
serverSock.bind(('', serverPort)) #Bind the socket to the port
serverSock.listen(1) #Start listening for incoming connections

print("The server is ready to receive...")
while True: #Forever accept incoming connections
ctrlSock, addr = serverSock.accept() #Accept a connection; get client's socket

while ctrlSock.recv(1) != '\x01': #Wait for 'hello'
continue
print("Connection established.")
while ctrlSock.send('\x01') < 1: #Reply 'hello', we're ready to accept commands
continue

cmd_id = None
while cmd_id != '\x02': #Keep accepting commands until 'quit'
cmd_id = None
while not cmd_id: #Wait for command
cmd_id = conSock.recv(1)
#Stuff goes here

while connSock.send('\x02') < 1: #Say 'goodbye'
continue
connSock.close()
print("Connection terminated.")

main() #Start the program


I've certainly failed the assignment. It's mostly personal curiosity at this point.

[itisnotlogical]

Programming networked applications makes me want to cry. Good luck and best wishes are all I have to offer

[Orange Wizard]

I think you might have to convert them into bytearrays, but there's something about needing to set encoding (i.e., utf8, etc.) and I don't know how to specify that.

Code: [Select]

b"this string is converted to a bytearray, usually UTF-8 encoding, I think"
bytes ("the bytes function will return an encoded bytearray", "utf-8")
I know zilch about networking though so I can't really help further.

[nogoodnames]

So I'm making a simple program to practice with C#. Right now it creates a board of hashes with arbitrary width and height and allows an ascii smileyface to move around it based on user input.

The problem is, every so often Visual Studio will hang when it tries to build the project. This happens randomly for no apparent reason. The build will start but not progress anywhere. VS won't allow me to abort the build, and it won't exit while a build is in progress so I have to end it via the task manager. After this happens, I won't be able to successfully build the project until I restart the computer. Other projects will still build correctly. I haven't done anything else this large, so I don't know if it's unique to this project or will happen with all C# projects.

Google has shown me people with similar problems, but not this exact one. Any ideas?
One possibility: both times it's happened, I had another instance of VS open with a Python project. Maybe it doesn't like working in two languages at once.

[RoguelikeRazuka]

Hey is here someone confident in SFML who can help? The thing is that I have a set of CircleShape objects and the one of Text objects. What I need to do is to simply place each of those "texts" (their strings are numbers) in the centre of each of the circles. Like this:


The code snippets I'm trying to succeed in it with:

Code: [Select]

Vector2f center(width/2.0f, height/2.0f);
float angle = 0.0f;
float step = M_PI*2.0f/n;
float vxShapeRadius = 20.0f

for (int i = 0; i < n; i++)
{
vxShapes[i]->setFillColor(Color::Blue);
vxShapes[i]->setOrigin(vxShapeRadius, vxShapeRadius);
vxShapes[i]->setPosition(center.x + 200.0f*cos(angle), center.y - 200.0f*sin(angle));
angle += step;
}

for (int i = 0; i < n; i++)
{
char buff[255] = {0};
nums[i].setFont(font);
nums[i].setColor(Color::Red);
nums[i].setCharacterSize(32);
nums[i].setString(_itoa(i+1,buff,10));
FloatRect numRect = nums[i].getGlobalBounds();
Vector2f numRectCenter(numRect.width/2.0, numRect.height/2.0);
nums[i].setOrigin(numRectCenter);
nums[i].setPosition(vxShapes[i]->getPosition().x, vxShapes[i]->getPosition().y);
}


Though I'm not getting what is needed. In which line(s) am I wrong?

vxShapes is an array of pointers to a CircleShape, nums is an array of Text objects.