My script runs on the shell but not on the command prompt

Question

I've recently started learning python from a book (invent your own computer games with python by Al Sweigart) and I'm trying to use stuff that I learn to modify exercises that I've done to make them more to my liking. Anyway, there was one such script which I tried to modify and while the modified version runs just the way I like it when I'm trying to run it using the interactive shell, when I double click the script icon to have it run on the command line interface(I hope I'm using the correct terminology so far cause I'm not really familiar with programming as of yet) it doesn't run. The command window opens and nothing happens.

Here's the original script that runs on both the shell and the command line:

import random
import time

def displayIntro():
    print('''You are in a land full of dragons. In front of you, you see two caves. in one cave, the dragon is friendly and will share his treasure with you. the other dragon is greedy and hungry and will eat you on sight.''')
    print()


def chooseCave():
    cave=''

    while cave != '1' and cave!='2':
        print('Which cave will you go into?(1 or 2)')
        cave=input()
    return cave


def checkCave(chosenCave):
    print('you approach the cave...')
    time.sleep(2)
    print('it\'s dark and spooky')
    time.sleep(2)
    print('a large dragon jumps out in front of you! he opens his jaws and...')
    print()
    time.sleep(2)
    friendlyCave=random.randint(1,2)

    if chosenCave==str(friendlyCave):
        print('gives you his treasure!')
    else:
        print('gobbles you down in 1 bite!')

playAgain = 'yes'

while playAgain=='yes' or playAgain=='y':
    displayIntro()
    caveNumber=chooseCave()
    checkCave(caveNumber)
    print('Do you want to play again?(yes or no)')
    playAgain=input()

And this is the modified version (I wanted the text to appear as being typed on the go to make it look more immersive:

import random
import time


def read(string):
    i=0
    while i<len(string):
        print(string[i],end='')
        time.sleep(0.05)
        if string[i]=='.':
            time.sleep(0.5)
        i=i+1
    print('')


def displayIntro():
    intro='''You are in a land full of dragons. In front of you, you see two caves. In one cave, the dragon is friendly and will share his treasure with you. The other dragon is greedy and hungry, and will eat you on sight.'''
    i=0
    read(intro)


def chooseCave():
    cave=''
    i=0
    question='Which cave will you go into? (1 or 2)'
    j=0
    print('')
    read(question)
    print('')

    while cave != '1' and cave != '2' and i<=10:
        cave = input()
        i=i+1
    return cave


def checkCave(chosenCave):
    approach='You approach the cave...'
    j=0
    read(approach)
    print()

    spooky='It\'s dark and spooky...'
    j=0
    read(spooky)

    time.sleep(1)
    print()
    print('\nA large dragon jumps out in front of you! He opens his jaw and...')
    time.sleep(1.5)

    friendlyCave=random.randint(1,2)

    if chosenCave == str(friendlyCave):
        print('Gives you his treasure!')
    else:
       print('Gobbles you down in one bite!')

playAgain='yes'

while playAgain=='yes' or playAgain== 'y':
    displayIntro()
    caveNumber=chooseCave()
    checkCave(caveNumber)
    print('Do you want to play again? (yes or no)')
    playAgain = input()

I tried removing the "end=''" part from the print(string[i],end='') line and it did run normally!(Although with terrible results as it typed 1 character per line!)

What do you think is the issue and how can I fix it without making it type a single character per line?

Thanks for your time! Bill

(Ps: during formatting the code for the post, I had to only indent lines that were not already intdented, so I think there might be an issue with indentation when trying to copy the code as some lines lack indentation? Anyway I hope this is not an issue)

Answer 1

You need to import sys and use sys.stdout.flush() function to get the flow of characters you want.

The read function should look like this

import random
import time
import sys


def read(string):
    i = 0
    while i < len(string):
        print(string[i], end='')
        time.sleep(0.05)
        if string[i] == '.':
            time.sleep(0.5)
        # flush stdout after sleep
        sys.stdout.flush()
        i = i + 1
    print('')

[... rest of the code ...]

It is good practice (PEP8) to have spaces between math symbols and conditional operators like the following

def chooseCave():
    [... code ...]
    i = 0
    [... code ...]
    while cave != '1' and cave != '2' and i <= 10:
        [... code ...]

Another PEP8 good practice is to not pass 79 maximum line length. So, when you have a really long string, one way to not pass the 79 characters is to do the following

def displayIntro():
    intro = ('You are in a land full of dragons. In front of you, you see two '
             'caves. In one cave, the dragon is friendly and will share his '
             'treasure with you. The other dragon is greedy and hungry, and '
             'will eat you on sight.')
    read(intro)

Answer 2

The print() statement at the end of "read" function will print a new line.

The whole code without the print():

import random
import time

def read(string):
    i=0
    while i<len(string):
        print(string[i],end='')
        time.sleep(0.05)
        if string[i]=='.':
            time.sleep(0.5)
        i=i+1

def displayIntro():
    intro='''You are in a land full of dragons. In front of you, you see two caves. In one cave, the dragon is friendly and will share his treasure with you. The other dragon is greedy and hungry, and will eat you on sight.'''
    i=0
    read(intro)
def chooseCave():
    cave=''
    i=0
    question='Which cave will you go into? (1 or 2)'
    j=0
    print('')
    read(question)
    print('')
    while cave != '1' and cave != '2' and i<=10:
        cave = input()
        i=i+1
    return cave

def checkCave(chosenCave):
    approach='You approach the cave...'
    j=0
    read(approach)
    print()
    spooky='It\'s dark and spooky...'
    j=0
    read(spooky)
    time.sleep(1)
    print()
    print('\nA large dragon jumps out in front of you! He opens his jaw and...')
    time.sleep(1.5)
    friendlyCave=random.randint(1,2)
    if chosenCave == str(friendlyCave):
        print('Gives you his treasure!')
    else:
        print('Gobbles you down in one bite!')

playAgain='yes'
while playAgain=='yes' or playAgain== 'y':
    displayIntro()
    caveNumber=chooseCave()
    checkCave(caveNumber)
    print('Do you want to play again? (yes or no)')
    playAgain = input()

Answer 3

Well... I tried to solve your problem. I wrote your code in my way but it works in the python shell but not in the command prompt window. However, here is my code:

import random as rnd
import time
import msvcrt

def read(string):
    for each in string:
        print(each, end="")
        time.sleep(0.05)

def displayIntro():

    intro="You are in a land full of dragons. In front of you, you see two caves. In one cave, the dragon is friendly and will share his treasure with you. The other dragon is greedy and hungry, and will eat you on sight."

    read(intro)



def chooseCave():
    cave=''
    print()

    while cave != '1' and cave!='2':

        read('Which cave will you go into?(1 or 2): ')

        cave=input()



    return cave


def checkCave(chosenCave):

    read('you approach the cave...')
    print()
    time.sleep(2)

    read("it's dark and spooky")
    print()
    time.sleep(2)

    read('a large dragon jumps out in front of you! he opens his jaws and...')
    print()
    print()

    time.sleep(2)



    friendlyCave=rnd.randint(1,2)



    if chosenCave==str(friendlyCave):

        read('gives you his treasure!')

    else:

        read('gobbles you down in 1 bite!')

    print()




playAgain="yes"
while playAgain=="yes" or playAgain=="y":
    displayIntro()
    caveNumber=chooseCave()
    checkCave(caveNumber)
    read("Do you want to play again? (yes/y or no/n): ")
    playAgain=input()
    playAgain=playAgain.lower()

print("Press any key to continue...")
while not msvcrt.kbhit():
    time.sleep(0.1)

I think you should learn GUI(Graphical User Interface) using tkinter (because using tkinter is simple and easy (at least for me)). If you learn GUI, you'll be able to make your programs more interesting.