tkinter syntax comprehension-CodePudding

I'm new and slowly been trying to learn some of tkinter and I've found a few nice resources for basic projects but the explanations of the codes have been a bit lacking and I'm hoping someone can help me understand a bit of what I've scrapped together.

full code

from tkinter import *

#Create window and give it title
root = Tk()
root.title('Tip Calculator - Charlie')

#define the window sizes
window_width = 600
window_height = 400
#get the screen size
screen_width = root.winfo_screenwidth()
screen_height = root.winfo_screenheight()
#solve for center of screen based on window & screen Size
center_x = int(screen_width/2 - window_width/2)
center_y = int(screen_height/2 - window_height/2)
#implement the above to position window width/height
root.geometry(f'{window_width}x{window_height} {center_x} {center_y}')


var = IntVar()
frame = LabelFrame(root,text = "Tip %")
frame.pack(pady=10)

r1 = Radiobutton(frame, text = 'no Tip', variable = var, value = 0)
r1.grid(column =0, row =1)
r2= Radiobutton(frame, text = '10 %', variable = var, value = 1)
r2.grid(column=0, row =2)
r3=Radiobutton(frame, text = '15 %', variable = var, value = 2)
r3.grid(column=1, row = 1)
r4= Radiobutton(frame, text = '20 %', variable = var, value =3)
r4.grid(column=1, row=2)

code in question

var = IntVar()
frame = LabelFrame(root,text = "Tip %")
frame.pack(pady=10)

r1 = Radiobutton(frame, text = 'no Tip', variable = var, value = 0)
r1.grid(column =4, row =1)
r2= Radiobutton(frame, text = '%', variable = var, value = 1)
r2.grid(column=4, row =2)

So I understand to an extent r1 is a variable name for the "Radiobutton", text is set to what pops up beside the button. The question is what does variable = var, value = 1 and the first 3 lines i'm at a loss why is a variable called var being created and what does setting it = IntVar() do?
Is frame a widget? I assume pack is another version of positioning (grid) ?

CodePudding user response：

This page will give you a nice explanation radio widget

Var is being used to establish an integer variabel as opposed to string variable. (IntVar() vs StringVar()). Read through the explanation in that documentation and let me know if it still doesn't make sense. As for you question on pack() its just a fast method that literally packs the widget in the center and top if you don't specify anything else.

CodePudding user response：

variable = var means that when the radio button is selected, the IntVar in the var variable should be given the value of this radio button. And the value option specifies the value that should be used for each radio button.

So after you select the no Tip radio button, var.get() will be 0. After you select the % button, var.get() will be 1. That's how you find out which choice they made with the radio buttons.

Later in the code you can write:

if var.get() == 0:
    tip = 0
elif var.get() == 1:
    tip = 0.10 * total_price
elif var.get() == 2:
    tip = 0.15 * total_price
elif var.get() == 3:
    tip = 0.20 * total_price

price_with_tip = total_price   tip

pack() is a geometry manager, an alternative to grid() and place(). See this tutorial

CodePudding user response：

To answer your follow up question I think this would help you for how to handle the next steps.

from tkinter import *

def get_value():
    tab = 50 # set to 50 but could get a value from entry if you want
   
    choice = var.get()
    print(choice) # print your choice for clarification
    ten_percent = tab * .1 # math for tip
    total = ten_percent   tab
    if choice == 1:
        print("Your total plus tip is:", total)
        print("Your tip amount was:", ten_percent)
    
#Create window and give it title
root = Tk()
root.title('Tip Calculator - Charlie')

#define the window sizes
window_width = 600
window_height = 400
#get the screen size
screen_width = root.winfo_screenwidth()
screen_height = root.winfo_screenheight()
#solve for center of screen based on window & screen Size
center_x = int(screen_width/2 - window_width/2)
center_y = int(screen_height/2 - window_height/2)
#implement the above to position window width/height
root.geometry(f'{window_width}x{window_height} {center_x} {center_y}')


var = IntVar()
frame = LabelFrame(root,text = "Tip %")
frame.pack(pady=10)

r1 = Radiobutton(frame, text = 'no Tip', variable = var, value = 0)
r1.grid(column =0, row =1)
r2= Radiobutton(frame, text = '10 %', variable = var, value = 1)
r2.grid(column=0, row =2)
r3=Radiobutton(frame, text = '15 %', variable = var, value = 2)
r3.grid(column=1, row = 1)
r4= Radiobutton(frame, text = '20 %', variable = var, value =3)
r4.grid(column=1, row=2)
button = Button(root, text="Check", command= get_value)
button.pack()