[Beginner] Programming Challenge: 2

[schauerlich]

???

From the article LaRoza linked to in the first post:

It happens that all string objects in Python have built-in methods which make this quite painless. Type these lines in at the '>>>' prompt:

>>>input = '9'
>>>input.isdigit()
1

This will return a '1' (true), so you can easily use it in an 'if' statement as a condition. Some other handy attributes of this kind are:

s.isalnum() returns true if all characters in s are alphanumeric, false otherwise.
s.isalpha() returns true if all characters in s are alphabetic, false otherwise.

[ghostdog74]

From the article LaRoza linked to in the first post:

I see. yes, isalnum, isalpha, isdigit all can be put to good use. Also the coder should take note that if characters such as # can be used in the username, then using isalnum() to check it will give you False.

[Def13b]

My attempt. Didn't want to use Try, Except though I think it might of been easier if I did. Didn't test it as thoroughly as I probably should of either but I think I covered all bases.

#!/usr/bin/env python

import sys

def name(input):
    if not input or input[0] == ' ':
        return False
    return True

def num(input, info):
    if input.isdigit():
        if input[0] not in ('0', '-'):
            if info == 'age' and int(input) > 130:
                return False
            return True

def input_data(info):
    options = {'age': '\nPlease enter your age: ',
               'name': '\nPlease enter your forum name: ',
               'fuid': '\nPlease enter your forum user ID: '}
    result = ''
    while not result:
        result = raw_input(options[info])
        if result.lower() == 'quit':
            print '\nExiting Program, Goodbye'
            sys.exit()
        if (info == 'age' or info == 'fuid') and num(result, info):
            return result
        if info == 'name' and name(result):
            return result
        result = ''
        print 'Invalid entry, please try again'


print "Welcome to the info gatherer. \
Type 'quit' at any prompt to exit the program"

name = input_data('name').strip()
age = input_data('age').strip()
fuid = input_data('fuid').strip()

print '\nYou are %s, aged %s, next year you will be %s, with user id \
%s the next user is %s' % (name, age, int(age)+1, fuid, int(fuid)+1) 

[cprofitt]

Here is my code... after much procrastination (read: several months) I am starting to take Python seriously... I have been told that this code is not very Pythonic... but I do believe it works properly.

#!/usr/bin/env python

#  challeng2.py
#       A program to handle text and numeric input
#  by PrivateVoid

import sys

sError = "there was an error in your entry please re-enter"
sBlank = "your entry was blank please re-enter"



def test(n):
        if n > 0 and n < 1000000 and n % 1 == 0:
                return True
        else:
                return False

def __exit__(s):
        if s == "exit":
                sys.exit(0)

def blank(r):
        if len(r) == 0:
                return True
        else:
                return False


def age():
        aInput = raw_input("how old are you? (must be an integer between 1 and 999999) ")
        try:
                __exit__(aInput)
                if blank(aInput):
                        print sBlank
                        return age()
                elif not test(int(aInput)):
                        print "your entry was not an integer between 1 and 999999 please re-enter"
                        return age()
                print aInput
                return int(aInput)
        except ValueError:
                print sError
                age()

def name():
        aName = raw_input("please enter your name (your name can not begin with a space) ")
        try:
                __exit__(aName)
                bName = aName.lstrip(' ')
                if len(aName) > len(bName):
                        print "your entry started with a space please re-enter"
                        return name()
                elif blank(aName):
                        print sBlank
                        return name()
                return aName                
        except ValueError:
                print sError
                name()

def forumid():
        aID = raw_input("please enter your forum ID (must be an integer between 1 and 999999) ")
        try:
                __exit__(aID)
                if not test(int(aID)):
                        print "your entry was not an integer between 1 and 999999 please re-enter"
                        return forumid()
                elif blank(aID):
                        print sBlank
                        return forumid()
                return int(aID)
        except ValueError:
               print sError
               forumid()

def main():
        print "To leave the program please just type 'exit' at any prompt"
        sName = name()
        sAge = age()
        sID = forumid()
        print "You are ", sName, " aged ", sAge, "next year you will be ", sAge+1, ", with user id ", sID, "the next user is ", sID+1, "."

main()

tools used - IDLE

can not wait for a critique and to see the other entries.

[ghostdog74]

def blank(r):
        if len(r) == 0:
                return True
        else:
                return False

to check for blank, there's no need to check for length

>>> s=""
>>> not s
True
>>> if not s:
...  print "null"
...
null

[code]
def name():
aName = raw_input("please enter your name (your name can not begin with a space) ")
try:
__exit__(aName)
bName = aName.lstrip(' ')
if len(aName) > len(bName):
print "your entry started with a space please re-enter"
....
[code]

to check starting with space, you can use startswith()

>>> s=" username"
>>> s.startswith(" ")
True

[Bachstelze]

Okay, here's my C version. Though it might seem a bit overkill, I used a separate header file for the sake of good practice.

challenge2.h

#ifndef CHALLENGE_2
#define CHALLENGE_2

#define MAX_AGE 130
#define MAX_UID 9999999
#define MAX_USERNAME_LENGTH 20

void initUser       (void);
void promptName     (void);
void promptAge      (void);
void promptUid      (void);
void printString    (void);
void destroyUser    (void);

#endif 

challenge2.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "challenge2.h"

/* The macros below are a little preprocessor trick to allow usage of other macro
 * values as string constants.
 * For more information, see:  http://gcc.gnu.org/onlinedocs/cpp/Stringification.html
 */

#define xstr(s) str(s)
#define str(s) #s


static char*    name;
static int      age;
static int      uid;

void initUser(void)
{
    //First, we initialize the variables
    name = (char*) calloc(MAX_USERNAME_LENGTH + 1, sizeof(char));
    age = 0;
    uid = 0;

    //Nice greeting message...
    printf("Okay, I'm going to ask you a few details about yourself.\n");
    printf("Remember that at any prompt, you may type \"exit\" to quit.\n\n");

    //And we prompt for the values
    promptName();
    promptAge();
    promptUid();
}


void testInputForExit(char* input)
{
    if(!strcmp(input, "exit"))
    {
        printf("Good bye!\n");
        exit(0);
    }
}


void cleanBuffer(void)
{
    /*  This is used to clean the buffer after every input, in order to avoid
     *  potential buffer overflow issues, as well not to pollute further inputs.
     */
    int c;
    while(((c = getchar()) != '\n') && c != EOF)
    {;}
}


int toInt(char* input, int max_value)
{
    /*  This function is used to check whether or not the string given as input
     *  is "convertible" to an integer. Unlike atoi() and friends, this requires
     *  _all_ the characters in the string to be digits. Since the minus sign is
     *  not allowed, only positive integers are. Additionally, this function also
     *  checks whether the converted integer is smaller than max_value.
     *
     *  This functions returns the converted positive integer on success.
     *  On failure, it returns -1 if the input was not a positive integer, and
     *  -2 if it exceeded the limit.
     */

    unsigned i = 0;
    while(i < strlen(input))
    {
        if(!isdigit(input[i]))
            return -1;
        i++;
    }

    return (atoi(input) > max_value) ? -2 : atoi(input);
}

char* prompt(unsigned maxStringLength)
{
    char* buffer = calloc(maxStringLength + 1, sizeof(char));
    unsigned i;

    /*  This is where the xstr macro comes into play. It allows us to always have
     *  a maximum input length sufficient to contain all the values, but no more
     *  (for the sake of simplicity, we assume that MAX_USERNAME_LENGTH will always
     *  be the longest one. Who needs twenty-digits ages anyway?).
     */
    scanf(" %" xstr(MAX_USERNAME_LENGTH) "[^\n]", buffer);
    cleanBuffer();

    //Remove trailing spaces (if any)
    for(i = strlen(buffer) - 1; i >= 0; i--)
    {
        if(isspace(buffer[i]))
            buffer[i] = '\0';
        else if(isgraph(buffer[i]))
            break;
    }

    testInputForExit(buffer);
    return buffer;
}


void promptName(void)
{
    printf("Please enter your username and press Enter.\n");
    char* tmp = prompt(MAX_USERNAME_LENGTH);
    memccpy(name, tmp, '\0', MAX_USERNAME_LENGTH);
    free(tmp);
}


void promptAge(void)
{
    printf("Now, please enter your age.\n");
    while(1)
    {
        char* tmp = prompt(MAX_USERNAME_LENGTH);
        if((age = toInt(tmp, MAX_AGE)) < 1)
        {
            if(age >= -1)
                printf("Error. Please enter a strictly positive integer.\n");
            else
                printf("Error. Please enter an integer lower than %u.\n", MAX_AGE);
        }
        else
            break;
    }
    free(tmp);
}


void promptUid(void)
{
    printf("Almost there! Now, please enter your user ID.\n");
    while(1)
    {
        char* tmp = prompt(MAX_USERNAME_LENGTH);
        if((uid = toInt(tmp, MAX_UID)) < 1)
        {
            if(uid >= -1)
                printf("Error. Please enter a strictly positive integer.\n");
            else
                printf("Error. Please enter an integer lower than %u.\n", MAX_UID);
        }
        else
            break;
    }
    free(tmp);
}


void printString(void)
{
    printf("You are %s, aged %d next year you will be %d, with user id %u the next user is %u.\n",
            name, age, age+1, uid, uid+1);
}


void destroyUser(void)
{
    printf("Good bye, %s!\n", name);
    free(name);
}


int main(void)
{
    initUser();
    printString();
    destroyUser();
    return 0;
} 

Place in the same directory and compile with

cc -o challenge2 challenge2.c

[PandaGoat]

My first attempt at using (common? maybe?) lisp. I tried it with scbl and clisp interpreters, and it worked. By the way it messed up with php tags, so I used code.

 
(defun check-name-nil (name)
  (if (STRING-EQUAL name "") t nil))

(defun check-name-start-space (name)
  (if (STRING-EQUAL (subseq name 0 1) " ") t nil))

(defun check-name-not-contains-char (name)
  (loop for c across name
     do (if (alpha-char-p c) (return-from check-name-not-contains-char nil) ()))
  t)


(defun get-name ()
  (loop
     do (format t "Whats be yo tag yo: ") (finish-output)
       (let ((name (read-line t)))
	 (if (STRING-EQUAL name "exit") (quit)
	     (if (check-name-nil name) (format t "Yuz ain't nosbody~%")  
		 (if (check-name-start-space name) (format t "Yuz tag gotta start wit a character yo~%")
		     (if (check-name-not-contains-char name) (format t "Yo i didn' ask fo yuz digits~%") (return-from get-name name))))))))



(defun get-age ()
  (loop
       do (format t "How old bez yo: ") (finish-output)
       (let ((age (read)))
	 (if (typep age 'REAL)
	     (if (<= age 0) (format t "Howz yuz typin' from da womb?~%") 
		 (if (>= age 120) (format t "Howz yuz not dead?~%") (return-from get-age age))) 	 
	     (if (STRING-EQUAL age "exit") (quit) (format t "Yuz age needzta be a numba~%"))))))
  


(defun get-id ()
  (loop
     do (format t "Whats yuz forum numba: ") (finish-output)
       (let ((id (read)))
	 (if (typep id 'REAL)
	     (if (<= id 0) (format t "No onez got dis forum numba~%") 
		 (if (> id 999999) (format t "No onez got dis forum numba~%") (return-from get-id id)))
	     (if (STRING-EQUAL id "exit") (quit) (format t "Yuz forum numba needzta be a numba~%"))))))


(defun main ()
  (format t "Follow da prompts or enta exit anywhere to exit~2%")
  (let ((name (get-name)) (age (get-age)) (id (get-id)))
    (format t "You are ~A, aged ~A next year you will be ~A, with user id ~A, the next user is ~A." name age (+ age 1) id (+ id 1))))


(main)

[artoj]

C++ again. I tried to abstract the validation of things as much as possible. This was good practice for using templates too.

#include <vector>
#include <string>
#include <iterator>
#include <iostream>
#include <sstream>

class ValidatorPolicy
{
    public:
        ValidatorPolicy() { }
        virtual ~ValidatorPolicy() { }
        
        virtual bool validate(int value) const = 0;
        virtual bool validate(const std::string& value) const = 0;

};

class FullPolicy : public ValidatorPolicy
{
    public:
        FullPolicy() { }
        virtual ~FullPolicy() { }

        virtual bool validate(int value) const { return true; }
        virtual bool validate(const std::string& value) const { return true; }

};

class RangePolicy : public FullPolicy
{
    public:
        RangePolicy(int min, int max)
        {
            m_min = min;
            m_max = max;
        }
        ~RangePolicy() { }

        bool validate(int value) const
        {
            if (value > m_min && value < m_max)
            {
                return true;
            }

            return false;
        }

    private:
        int m_min;
        int m_max;

};

class NamePolicy : public FullPolicy
{
    public:
        NamePolicy() { }
        ~NamePolicy() { }

        bool validate(const std::string& value) const
        {
            if (value[0] == ' ' || value.empty())
                return false;

            return true;
        }

};

template <typename T> class Validator
{
    public:
        Validator() { }
        ~Validator()
        {
            while (!m_policies.empty())
            {
                delete m_policies.back();
                m_policies.pop_back();
            }
        }

        void addPolicy(ValidatorPolicy* policy)
        {
            m_policies.push_back(policy);
        }

        bool validateAll(const T& value)
        {
            std::vector<ValidatorPolicy*>::iterator i;
            for (i = m_policies.begin(); i != m_policies.end(); ++i)
            {
                if (!isValid((*i), value))
                    return false;
            }

            return true;
        }

        bool isValid(ValidatorPolicy* policy, const T& value)
        {
            return policy->validate(value);
        }
    
    private:
        std::vector<ValidatorPolicy*> m_policies;    
};

class Application
{
    public:
        Application() { }
        virtual ~Application() { }

        virtual int exec() = 0;

};

class ValidatorApplication : public Application
{
    public:
        ValidatorApplication()
        {
            m_nameValidator.addPolicy(new NamePolicy());
            m_ageValidator.addPolicy(new RangePolicy(5, 120));
            m_forumIdValidator.addPolicy(new RangePolicy(0, 99999));
        }

        ~ValidatorApplication() { }

        int exec()
        {
            std::cout << "Type your info or \"exit\" to exit."
                << std::endl << std::endl;

            std::string s;
            
            do
            {
                if (!input("Please input your name: ", s))
                {
                    return 0;
                }
                else
                {
                    m_name = s;
                }
            }
            while (!m_nameValidator.validateAll(m_name));

            do
            {
                if (!input("Plese input your age: ", s))
                {
                    return 0;
                }
                else
                {
                    std::istringstream stream(s);
                    stream >> m_age;
                }
            }
            while (!m_ageValidator.validateAll(m_age));

            do
            {
                if (!input("Please input your forum id: ", s))
                {
                    return 0;
                }
                else
                {
                    std::istringstream stream(s);
                    stream >> m_forumId;
                }
            }
            while (!m_forumIdValidator.validateAll(m_forumId));

            std::cout << "You're " << m_name << " aged " << m_age << " next ";
            std::cout << "near you'll be " << m_age + 1 << ", with user id ";
            std::cout << m_forumId << ", the next user is " << m_forumId + 1;
            std::cout << std::endl;

            return 0;
        }
    
    private:
        bool input(const std::string& prompt, std::string& command)
        {
            std::cout << prompt;
            getline(std::cin, command);

            if (command == "exit")
                return false;
            
            return true;
        }

        std::string m_name;
        int m_age;
        int m_forumId;
        Validator<std::string> m_nameValidator;
        Validator<int> m_ageValidator;
        Validator<int> m_forumIdValidator;

};

int main(int argc, char* argv[])
{
    ValidatorApplication app;
    return app.exec();
} 

[Ed J]

Now that I'm done I'll look at the other entries.

#!/usr/bin/env python

runiftrue = 1
while runiftrue: 
    while 1:    
        try:
            namein = raw_input('Enter your name, press "Enter" when complete. ')
            if len(namein) == 0:
                print 'Not enough characters.'
                continue
            if namein[0] == ' ':
                print "Don't start name with a space."
                continue
            if namein == "quit":
                print 'Goodbye' 
                runiftrue = 0
                break
            if len(namein) > 20:
	        namein = namein[0:19]  
                print 'name truncated'  
            break
        except:
	    print 'Input error, try again.'
            continue

    if runiftrue == 0:
        break

    while 1:    
        try:
            agein = raw_input('Enter your age, press "Enter" when complete. ')
            if len(agein) == 0:
                print 'Not enough characters.'
                continue
            if agein == "quit":
                print 'Goodbye'
	        runiftrue = 0
                break
            if not agein.isdigit():
                print 'Enter a number for your age.'
                continue
            if int(agein) < 1:
                print 'Too low, try again.'
                continue
            break
        except:
	    print 'Input error, try again.'
            continue

    if runiftrue == 0:
        break

    while 1:
        try:
            useridin = raw_input('Enter your Forum User ID, press "Enter" when complete. ')
            if useridin == "quit":
                print 'Goodbye'
	        runiftrue = 0
                break
            if len(useridin) == 0:
                print 'Not enough numbers.'
                continue
            if not useridin.isdigit():
                print 'Enter the number of your Forum User ID.'
                continue
            if int(useridin) > 999999:
                print 'Too high, try again.'
                continue
            if int(useridin) < 1:
                print 'Too low, try again.'
                continue
            if len(useridin) > 20:
	        useridin = useridin[0:19]  
                print 'name truncated'  
            break
        except:
            print 'Input error, try again.'
            continue

    if runiftrue == 0:
        break
    
    print '''You are %s, age %i, next year you will be %i, with user id %i,
        the next user is %i.''' % (namein, int(agein), int(agein)+1,                            
        int(useridin), int(useridin) + 1)
    break

[Bachstelze]

Wow, that's a lof of if's