[Beginner] Programming Challenge: 2

[TreeFinger]

class ForumUser:

    def __init__(self):
        print "Welcome, new forum user! We must set up your account."
        print "To exit the setup at anytime, simply type 'exit' (excluding quotations)."

        self.name = ""
        self.age = -1
        self.user = -1

        self.__set_all()

        self.to_string()

    def __set_all(self):
        print "The first step is to set your user name.\n"
        self.set_name()

        print "Next, please enter your age.\n"
        self.set_age()

        print "Finally, enter your user ID.\n"
        self.set_user()

    def set_name(self):
        print "Forum Name must have at least 1 character, may not begin with a space and cannot be 'exit', 'Exit', etc.\n"
        name_ok = False
        while name_ok == False:
            self.name = raw_input("Enter Desired Name: ")
            self.__y_n_exit(self.name)

            if self.name == "":
                print "I told you, your name must be at least 1 character long!\n"
                continue
            if self.name[0] == " ":
                print "I told you, space as first character is not allowed!\n"
                continue
            else:
                name_ok = True
                print "Your user name is: %s \n " % self.name

    def set_age(self):
        print "Your age must be a number greater than 0, although I have a feeling you are much older than 1!\n"
        age_ok = False
        while age_ok == False:
            self.age = raw_input("Enter Your Age: ")
            self.__y_n_exit(self.age)

            self.age = self.__string_to_int(self.age)

            if self.age == 'error': 
                continue
            elif self.age < 1:
                print "You aren't that young! Enter your real age!\n"
                continue
            elif self.age > 199:
                print "I don't think anyone is that old! Enter your real age!\n"
                continue
            else:
                age_ok = True
                print "Your age is: %d" % self.age

    def set_user(self):
        print "Your user ID must be greater than 0 and less than 999999\n"
        userid_ok = False
        while userid_ok == False:
            self.user = raw_input("Enter Your ID: ")
            self.__y_n_exit(self.user)

            self.user = self.__string_to_int(self.user)

            if self.user == 'error':
                continue
            elif self.user < 1:
                print "ID Must be greater than 0!\n"
                continue
            elif self.user > 999999:
                print "ID Must be less than 1000000!\n"
                continue
            else:
                userid_ok = True
                print "Your ID is: %d" % self.user

    def to_string(self):
        if self.user != 999999:
            print "You are %s, aged %d, with user id %d. Next year you will be %d and the next user id is %d" % (self.name, self.age, self.user, self.age+1, self.user+1)
        else:
            print "You are %s, aged %d, with user id %d. Next year you will be %d and there can be no next user!" % (self.name, self.age, self.user, self.age+1)

    def __string_to_int(self, string):
        try:
            return int(string)
        except ValueError:
            print "I don't think you entered a normal number! Try Again."
            return 'error'

    def __y_n_exit(self, string):
        if string.lower() == 'exit':
            print "\nYou have decided to exit, come back soon!"
            quit()

user = ForumUser() 

[Bachstelze]

Quick Python version, I'll work on a C one after dinner

#!/usr/bin/env python
#coding: utf-8

import sys

class User(object) :

    def __init__(self) :
        self.__username = ""
        self.__uid = 0
        self.__age = 0

        print "Okay, I'm going to ask you a few details about yourself."
        print "Remember that at any prompt, you may type \"exit\" to quit."

    def testInputForExit(self, input) :
        if input == "exit" :
            print "Good bye!"
            sys.exit(0)


    def promptUsername(self) :
        print "\nPlease enter your username and press Enter."
        while True :
            username = raw_input()
            self.testInputForExit(username)
            username=username.strip()

            if username != "" :
                self.__username = username
                break

            print "Error. Your username must contain at least one non-space character."


    def promptAge(self) :
        print "\nNow, please enter your age."
        while True :
            age = raw_input()
            self.testInputForExit(age)

            try :
                age = int(age)
                assert age >= 0 and age <= 130
            except ValueError :
                print "Error. You must enter an integer."
            except AssertionError :
                print "Error. You must enter a stricly positive integer no greater than 130."
            else :
                self.__age = age
                break

    def promptUid(self) :
        print "\nAlmost there! Now, please enter your user ID."
        while True :
            uid = raw_input()
            self.testInputForExit(uid)

            try :
                uid = int(uid)
                assert uid > 0
            except ValueError :
                print "Error. You must enter an integer."
            except AssertionError :
                print "Error. You must enter a strictly positive integer."
            else :
                self.__uid = uid
                break

    def printString(self) :
        print "You are %s, aged %s next year you will be %s, with user id %s, the next user is %s." % \
                (self.__username, self.__age, self.__age + 1, self.__uid, self.__uid +1)

if __name__ == "__main__" :
    user = User()
    user.promptUsername()
    user.promptAge()
    user.promptUid()
    user.printString()

[Titan8990]

Alright, starting off. I am aware that it better practice to use OPP instead of global variables but this is the way that I wanted to do it for my own personal learning experience. I'm happy with the end result:

#!/usr/bin/python

import sys

name = 0
age = 0
uid = 0

def getname():
    global name
    name = raw_input(str("What is your name? "))
    if name == "exit":
        sys.exit()        
    if name[0] == " ":
        print "\nPlease do not start your name with a space.\n\nTry again.\n"
        getname()
    try:
        name = str(name)
    except:
        print "\nAre you sure thats your name?\n\nTry again.\n"
        getname()
    
def getage():
    global age
    age = raw_input("How old are you? ")
    
    if age == "exit":
        sys.exit()
    
    try:
        age = int(age)
    except:
        print "\nYour age needs to be an integer.\n\nTry again.\n"
        getage()
    if age > 100:
        print "\nThats too old.\n\n Try again.\n"
        getage()
    elif age <= 0:
        print "\nYou must be older than that.\n\nTry again.\n"
        getage()
        

def getuid():
    global uid
    uid = raw_input("What is your forum user id? ")

    if uid == "exit":
        sys.exit()
    
    try:
        uid = int(uid)
    except: 
        print "\nUser IDs should be in the form of integers\n"
        getuid()
    if uid < 1:
        print "\nThe user ID you have entered is invalid.\n\nTry again.\n"
        getuid()
    elif uid > 999999:
        print "\nThe user ID you have entered in invalid.\n\nTry again.\n"
        getuid()        


def main():

    print "\n\nPlease answer the following questions.\n\n You can type exit at any time to quit.\n"
    getname()
    getage()
    getuid()

    nextyear = age + 1
    nextuid = uid + 1

    print "\n\nYou are %s, aged %s next year you will be %s, with user id %s, the next user is %s.\n" % (name, age, nextyear, uid, nextuid)

    raw_input("Press the enter key to exit.\n")

main() 

[wtfnomorenames]

After a few hours of me banging my head against anything that was in close proximity, reading through man page after man page, and wasting even a few more hours trying to figure out why fflush() wasn't working on stdin, I think I finally have some working code here.

It was compiled using gcc 4.2.3 on Linux 2.6.24-19.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <ctype.h>

#define NAME_LEN 21
#define BUF_SIZE 21

#define AGE_MIN 10
#define AGE_MAX 100

#define ID_MIN 1
#define ID_MAX 999999

#define QUIT_STRING "exit"

void get_string(char* prompt, char* string, unsigned int string_length)
{
  char buffer[BUF_SIZE];
  char c;

  printf("%s", prompt);

  /* Read in BUF_SIZE characters from standard input and store it in buffer. */
  fgets(buffer, BUF_SIZE, stdin);

  /* If the user types "exit" at any point, then that's what we need to do. */
  if (strncmp(buffer, QUIT_STRING, strlen(QUIT_STRING)) == 0)
    exit(EXIT_SUCCESS);

  /* This code could use some explaining. What happens when you type in a
     string longer than the buffer is that it copies over the length of the
     buffer, but leaves the rest of what was entered still in the input queue.
     For most compilers, fflush() is only designed for output buffers, and
     using it on input buffers has an unknown effect. (However, I believe that
     MS VC++'s version of fflush may be used on stdin.) What this code does is
     (1) checks to see if our local buffer string is full, and (2) if this is
     the case, then that means we have some "overflow" still in the stdin
     queue. The while loop then reads in the rest of the unwanted characters
     from the queue and discards them, so we won't have problems when we try
     and read new user input in the future. */
  if (strlen(buffer) >= BUF_SIZE - 1)
    while ((c = fgetc(stdin)) && c != '\n');

  /* Copies our local copy to the string whose address was passed in. This
     only copies up to string_length characters. */
  strncpy(string, buffer, string_length);
}

void get_username(char* prompt, char* string, unsigned int string_length)
{
  char username[BUF_SIZE];
  int hasChars = 0;
  int i;

  do {
    get_string(prompt, username, BUF_SIZE);

    if (username[0] == ' ') {
      printf("Sorry, your username cannot begin with a space.\n");
      continue;
    }

    /* This scans the string to see if there is at least one character (as
       opposed to all numbers) in the string. In addition, it gets rid of the
       newline character which is kept on from the fgets() function called in
       the get_string function. */
    for (i = 0; i < BUF_SIZE; i++) {
      if (username[i] == '\n'){
    username[i] = '\0';
    break;
      }

      if (isalpha(username[i])) {
    hasChars = 1;
      }
    }

    if (! hasChars)
      printf("Sorry, your username must contain at least 1 character.\n");

  } while ((! hasChars) || username[0] == ' ');

  strncpy(string, username, string_length);
}

unsigned int get_number(char* prompt, unsigned int min, unsigned int max)
{
  char input_string[BUF_SIZE];

  unsigned int number = 0;

  do {
    printf("%s (%d-%d): ", prompt, min, max);
    get_string("", input_string, BUF_SIZE);
    
    /* Converts the string representation of the number to an actual integer
       stored value. */
    number = (unsigned int)atoi(input_string);

    /* atoi will return 0 if an error has occured, so we must check the first
       character to see if it is actually a 0, or if atoi just returned with an
       error. */
    if (number == 0 && input_string[0] != '0') {
      printf("That wasn't a number. Please try again.\n");
      continue;
    }
  } while (number < min || number > max);

  return number;
}

int main(int argc, char* argv[])
{
  char name[NAME_LEN]; name[0] = '\0';
  unsigned int age, id;

  /* We want to make sure that the quit string can actually fit inside the
     buffer. Otherwise, all hell may break lose. */
  assert(strlen(QUIT_STRING) < BUF_SIZE);

  printf("Type '%s' at any time to quit.\n\n", QUIT_STRING);

  /* Retrieve and validate all input */
  age = get_number("Please enter your age", AGE_MIN, AGE_MAX);
  id = get_number("Please enter your user id", ID_MIN, ID_MAX);
  get_username("Please enter your forum name: ", name, NAME_LEN);
  
  /* Output the final results */
  printf("You are %s, aged %d next year you will be %d, with user id %d, the next user is %d.\n", name, age, age+1, id, id+1);

  /* We are home at last! */
  return EXIT_SUCCESS;
} 

EDIT: I changed the CODE tags to PHP tags, so the code is easier on your eyes, even though the OCD side of me is making me twitch because it's labeled something that it's not.

[LaRoza]

@wtfnomorenames

It prints "Sorry, your username must contain at least 1 character." every time. Please fix it, I'd hate to have your code disqualified for such a minor detail

[wtfnomorenames]

@wtfnomorenames

It prints "Sorry, your username must contain at least 1 character." every time. Please fix it, I'd hate to have your code disqualified for such a minor detail

Wow, thanks for that! I restructured some things, and didn't even notice that. I corrected it in my post above.

[Bachstelze]

@LaRoza : not sure if we may comment on other users' code here. If not, feel free to delete this.

@Titan8990 : okay, a few comments:

1) "Shebang" line. You should use #!/usr/bin/env python instead of #!/usr/bin/python, because Python is not always intalled at /usr/bin/python. For example, if I tried to execute your script on my FreeBSD system, it would not start, because Python is intalled at /usr/local/bin/python. On the other hand, #!/usr/bin/env python is a nice way to make sure your script runs on all platforms (see here if you want to know why).

2) Global variables. You really shouldn't use them, and you can avoid it without needing to use OOP, just pass the variables you need to be modified as arguments to your function, and use the return values, like :

age = 0
    
def getage(oldage):
    age = raw_input("How old are you? ")
    
    if age == "exit":
        sys.exit()
    
    try:
        age = int(age)
    except:
        print "\nYour age needs to be an integer.\n\nTry again.\n"
        getage()
    if age > 100:
        print "\nThats too old.\n\n Try again.\n"
        getage()
    elif age <= 0:
        print "\nYou must be older than that.\n\nTry again.\n"
        getage()

    return age

def main(age):

    print "\n\nPlease answer the following questions.\n\n You can type exit at any time to quit.\n"
    age = getage(age)
    nextyear = age + 1

    print "\n\nYou are aged %s next year you will be %s." % (age, nextyear)

    raw_input("Press the enter key to exit.\n")

main(age) 

3) Recursivity. It is absolutely not needed here, as it doesn't make your code any more readable, and could lead to problems if you have some fool of a user who keeps entering invalid data, due to the enormous amount of function calls in your stack that would create. It would be better to use a while loop to keep prompting until a valid value is entered without making additional function calls.

4) str(x) when x is a string (you're not the only one who've done that one, though). What the heck? If x is a string, str(x) will simply return x, there is absolutely no point in doing this (and even more so in trying to make it raise an exception) when you're certain it is the case.

5) name = 0. Setting an initial value for a parameter that is not of the correct type for it (0 is an illegal name, as it is not a string) should be avoided, as it might confuse people who read your code and might want to reuse it.

[linkmaster03]

Should we let usernames contain spaces as long as it does not begin with a space?

[LaRoza]

Wow, thanks for that! I restructured some things, and didn't even notice that. I corrected it in my post above.

I'll test it out. It works well, definately one of the top ten assuming we don't get a bunch of C guru's here

@LaRoza : not sure if we may comment on other users' code here. If not, feel free to delete this.

Why not. It is all about learning.

1) "Shebang" line.

Just to let others know, I copy and paste code to run it, but I will run it with the appropriate interpreter even if it isn't specified or specified correctly.

Should we let usernames contain spaces as long as it does not begin with a space?

User names can contain spaces, but as long as the program doesn't break when it is entered (even if it doesn't record the name in full) it is Ok. Using spaces will be a possible tie breaker if it comes down to that.

[kk0sse54]

First program ever written with python these threads are an awesome idea

#! /usr/bin/python

import sys
resp = raw_input("What is your forum name (Type quit to exit)? ")
if resp == "quit":
    print "Goodbye"
    sys.exit()
else:
    print "Thank You"

resp1 = raw_input("What is your age (Type quit to exit)? ")
if resp1 == "quit":
    print "Goodbye"
    exit()
else:
    resp1 = int(resp1)
    if resp1 < 1:
        print "That is not a valid age, Goodbye"
        exit()
    else:
        if resp1 > 999999:
            print "That is not a valid age,Goodbye"
            exit()
        else:
            print "Thank You"

resp2 = raw_input("What is your forum ID (Type quit to exit)? ")
if resp2 == "quit":
    print "Goodbye"
    exit()
else:
    resp2 = int(resp2)
    if resp2 < 1:
        print "That is not a valid forum ID, Goodbye"
        exit()
    else:
        if resp2 > 999999:
            print "That is not a valid forum ID, Goodbye"
            exit()
        else:
            print "Thank You"

print "You are %s, aged %s next year you will be %s, with user id %s, the next user is %s." % (resp, resp1,resp1 + 1, resp2, resp2 +1)