GUI_calculator.py

import tkinter as tk   # standard Python interface to create graphical user interfaces (GUIs)

calculation = ""   #store the ongoing input from the user as they enter numbers and operators.

def add_to_calculation(symbol):
    global calculation 
    calculation += str(symbol) # converts the symbol to a string and appends it to the ongoing calculation.
    text_result.delete(1.0, "end") # used in many GUI applications to clear output or reset a text area before inserting new data.
    text_result.insert(1.0, calculation) #Inserts the current calculation string into the display area starting from the first position.



def evalute_calculation():# the expression stored in the calculation variable when the user presses the "=" button
    global calculation 

    try:
        calculation = str(eval(calculation))
#Python's eval() function,If an error occurs, it clears the field and shows "Error". However, be careful with eval() due to potential security risks if users input malicious code.        
        text_result.delete(1.0, "end")
        text_result.insert(1.0, calculation)
    except:
         clear_field()
         text_result.insert(1.0, "Error")

        

def clear_field():# used to clear the input field, resetting the calculator to its initial state when the user presses the "C" button.
    global calculation
    calculation = ""
    text_result.delete(1.0, "end")


def backspace(): # Add a backspace functionality to remove the last character of the current calculation.
    global calculation
    calculation = calculation[:-1]
    text_result.delete(1.0, "end")
    text_result.insert(1.0, calculation)



root = tk.Tk()# initialize the main application window.
root.geometry("323x300")#dimensions of the calculator window to 323 pixels wide and 359 pixels tall. The * should be replaced by x (the correct separator for specifying dimensions).
root.title("GUI Calculator using tkinter")

text_result = tk.Text(root, height =2, width=18, font=("Aerial",23))
text_result.grid(columnspan=5)#Creates a text widget (display area) with specified height, width, and font.


btn_1 = tk.Button(root, text="1", command=lambda:add_to_calculation(1), width=5, font=("Aerial",14))
btn_1.grid(row=2, column=1)
#Buttons like btn_1, btn_2, etc., are created using tk.Button() and configured to trigger the add_to_calculation() function with specific numbers or operators. grid() arranges them on the screen.
btn_2 = tk.Button(root, text="2", command=lambda:add_to_calculation (2), width=5, font=("Aerial",14))
btn_2.grid(row=2, column=2)
btn_3 = tk.Button(root, text="3", command=lambda:add_to_calculation(3), width=5, font=("Aerial",14))
btn_3.grid(row=2, column=3)
btn_4 = tk.Button(root, text="4", command=lambda:add_to_calculation(4), width=5, font=("Aerial",14))
btn_4.grid(row=3, column=1)
btn_5 = tk.Button(root, text="5", command=lambda:add_to_calculation(5), width=5, font=("Aerial",14))
btn_5.grid(row=3, column=2)
btn_6 = tk.Button(root, text="6", command=lambda:add_to_calculation(6), width=5, font=("Aerial",14))
btn_6.grid(row=3, column=3)
btn_7 = tk.Button(root, text="7", command=lambda:add_to_calculation(7), width=5, font=("Aerial",14))
btn_7.grid(row=4, column=1)
btn_8 = tk.Button(root, text="8", command=lambda:add_to_calculation(8), width=5, font=("Aerial",14))
btn_8.grid(row=4, column=2)
btn_9 = tk.Button(root, text="9", command=lambda:add_to_calculation(9), width=5, font=("Aerial",14))
btn_9.grid(row=4, column=3)
btn_0 = tk.Button(root, text="0", command=lambda:add_to_calculation(0), width=5, font=("Aerial",14))
btn_0.grid(row=5, column=2)


btn_plus = tk.Button(root, text="+", command=lambda:add_to_calculation("+"), width=5, font=("Aerial",14))
btn_plus.grid(row=2, column=4)
btn_minus = tk.Button(root, text="-", command=lambda:add_to_calculation("-"), width=5, font=("Aerial",14))
btn_minus.grid(row=3, column=4)
btn_mul = tk.Button(root, text="*", command=lambda:add_to_calculation("*"), width=5, font=("Aerial",14))
btn_mul.grid(row=4, column=4)
btn_div = tk.Button(root, text="/", command=lambda:add_to_calculation("/"), width=5, font=("Aerial",14))
btn_div.grid(row=5, column=4)


btn_open = tk.Button(root, text="(", command=lambda:add_to_calculation("("), width=5, font=("Aerial",14))
btn_open.grid(row=5, column=1 )
btn_close = tk.Button(root, text=")", command=lambda:add_to_calculation(")"), width=5, font=("Aerial",14))
btn_close.grid(row=5, column=3)


btn_equals = tk.Button(root, text="=", command=evalute_calculation, width=6, font=("Aerial",14))
btn_equals.grid(row=6, column=2,columnspan=2)
btn_clear = tk.Button(root, text="C", command=clear_field, width=6, font=("Aerial",14))
btn_clear.grid(row=6, column=0,columnspan=2)
btn_clearbutton = tk.Button(root, text="Back", command=backspace, width=6, font=("Aerial",14))
btn_clearbutton.grid(row=6, column=4, columnspan=2)


root.mainloop()#keeps the window open and allows the GUI to respond to user inputs.