Python: why the surface.blit function doesn't display all inputs?

Question

I am trying to write a little digits game using pygame. The idea of the game is to guess the four-digit number randomly chosen by computer. But I am stuck at the very beginning I started by creating all the essential elements: colours, fonts, surfaces, etc. I used blit to 'simulate' computer choice and to show the user's guess. And interestingly enough, not all the inputs are displayed. E.g. '1234' and '9999' is displayed. However, '5738' and '7365' are not. Looking forward to hearing opinions of the experienced users.

import random
import pygame

pygame.init()

width = 900
height = 500
black = (0,0,0)
pastel_blue = (200,205,230)

win = pygame.display.set_mode((width,height))
pygame.display.set_caption("Bulls and Cows")
digit_font = pygame.font.SysFont('comicsans', 30)

a = (random.randint(1000, 10000))
print(a)

def display():
    win.fill((pastel_blue))

    number = digit_font.render("_ _ _ _", 1, black)
    win.blit(number, (width//2-number.get_width()//2, height//4))
    pygame.display.update()

display()

def guess_number():
    global c
    c = input("Guess the number: ")
guess_number()

def guess_display():
    text = digit_font.render(c, 1, black)
    print(text.get_width()//2)
    win.blit(text, [width//2-text.get_width()/2, 300])  #this seems to be the part that doesn't work correctly
    pygame.display.update()
    pygame.time.delay(2000)

guess_display()

Answer 1

You have to handle the events in the application loop. See pygame.event.get() respectively pygame.event.pump():

For each frame of your game, you will need to make some sort of call to the event queue. This ensures your program can internally interact with the rest of the operating system.

def guess_display():
    text = digit_font.render(c, 1, black)
    print(text.get_width()//2)
    win.blit(text, [width//2-text.get_width()/2, 300])  #this seems to be the part that doesn't work correctly
    pygame.display.update()
    pygame.event.pump()          # <---
    pygame.time.delay(2000)

---

However, the usual way is to use an application loop. Also see Why is my PyGame application not running at all?:

def guess_display():
    text = digit_font.render(c, 1, black)
    print(text.get_width()//2)

    run = True
    while run:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False
    
        win.blit(text, [width//2-text.get_width()/2, 300])
        pygame.display.update()

---

Also see:

• Why is my display not responding while waiting for input?
• Why does pygame.display.update() not work if an input is directly followed after it?
• How to create a text input box with pygame?