Code Execution Causes Undefined btn_click Error

If you enter the following code in Python 3, you get the error "btn_click is not defined", and btn2_click is not defined in the same way.

Where should I change to work without errors?

import tkinter
# screen creation
tki=tkinter.Tk()
tki.geometry('400x200')# Screen Size Settings
tki.title('Gacha')# Setting the Screen Title

# Create Buttons
btn=tkinter.Button(tki, text='single shot', height=2, width=20, command=btn_click)# Button Settings
btn.place(x=30,y=100)# Button Location
btn2=tkinter.Button(tki, text='10', height=2, width=20, command=btn2_click)# Button Settings
btn2.place(x=230,y=100)# Button Location
  
defbtn_click():
    import tkinter
    tki2 = tkinter.Tk()
    tki2.geometry ('400x200')
    tki2.title('1')
    btn3 = tkinter.Button(tki2, text='yes', height=2, width=20)# Button Settings
    btn4 = tkinter.Button(tki2, text='no', height=2, width=20)
    btn3.place(x=30,y=100)
    btn4.place(x=230,y=100)

defbtn2_click():
    import tkinter
    tki3 = tkinter.Tk()
    tki3.geometry ('400x200')
    tki3.title('10')
    btn5 = tkinter.Button(tki2, text='yes', height=2, width=20)# Button Settings
    btn6=tkinter.Button(tki2, text='no', height=2, width=20)
    btn5.place(x=30,y=100)
    btn6.place(x=230,y=100)

# Display screen as it
tki.mainloop()

python python3

2022-11-21 15:08

2 Answers

It's not limited to Python, it's usually an error when referenced before using variables (especially in dynamic typing languages).
Defining it right there, but don't look backward when you run it

result=hed+v*3#👈Error because it deals with undefined variables

had = 1
v = 2
print(result)

Also, it is the same even if it is not a variable but not a variable.Don't browse before defining a function
The question btn_click is undefined at the time of "Create Button" execution

result=fn#👈Error handling function fn before definition

However, the situation is slightly different in the following cases

fndefining the function, v is not an error
functionfnRun (on call) tries to browse to hed, v, so if undefined at that time, error

In this case, the order is fn definition -->hed, v definition --> subsequently calling fn(), so no errors occur

本来 Originally hed, v should be given by argument, but this structure for reference description

deffn():
    result=hed+v*3
    return result

had = 'Ah'
v=' is '
print(fn())
had = 'Yes'
v='To'
print(fn())

2022-11-21 17:05

As noted, calling btn_click on a line prior to defining btn_click results in NameError as shown below.

Exception has occurred:NameError
name 'btn_click' is not defined

By the way, btn5=tkinter.Button(tki2,text='yes',height=2,width=20) also generates NameError.
This is because tki2 is not defined within the scope of the btn2_click function.
Make sure that tki3 is typed incorrectly.

We verified normal operation by rewriting it like a sample code.

sample code

import tkinter
# screen creation
tki=tkinter.Tk()
tki.geometry('400x200')# Screen Size Settings
tki.title('Gacha')# Setting the Screen Title

defbtn_click():
    import tkinter
    tki2 = tkinter.Tk()
    tki2.geometry ('400x200')
    tki2.title('1')
    btn3 = tkinter.Button(tki2, text='yes', height=2, width=20)# Button Settings
    btn4 = tkinter.Button(tki2, text='no', height=2, width=20)
    btn3.place(x=30,y=100)
    btn4.place(x=230,y=100)

defbtn2_click():
    import tkinter
    tki3 = tkinter.Tk()
    tki3.geometry ('400x200')
    tki3.title('10')
    btn5=tkinter.Button(tki3,text='yes',height=2,width=20)# Button Settings
    btn6=tkinter.Button(tki3, text='no', height=2, width=20)
    btn5.place(x=30,y=100)
    btn6.place(x=230,y=100)

# Create Buttons
btn=tkinter.Button(tki, text='single shot', height=2, width=20, command=btn_click)# Button Settings
btn.place(x=30,y=100)# Button Location
btn2=tkinter.Button(tki, text='10', height=2, width=20, command=btn2_click)# Button Settings
btn2.place(x=230,y=100)# Button Location

# Display screen as it
tki.mainloop()

2022-11-21 17:31

If you have any answers or tips

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