app.py

import streamlit as st

def calculate(expression):
    """
    Calculates the mathematical expression using a safer approach
    than eval().

    Args:
        expression (str): The mathematical expression to be evaluated.

    Returns:
        float: The result of the calculation, or None if an error occurs.
    """

    try:
        # Use ast.literal_eval() for a more secure evaluation
        result = ast.literal_eval(expression)
    except (SyntaxError, ValueError):
        return None  # Indicate an error

    return result

st.set_page_config(page_title="Beautiful Calculator", page_icon="calculator")
st.title("Beautiful Calculator")

# Use columns for a visually appealing layout
col1, col2 = st.columns(2)

# Create input fields for numbers and expression
num1 = col1.number_input("First Number", key="num1")
num2 = col2.number_input("Second Number", key="num2")
user_expr = st.text_input("Enter Expression (e.g., +,-,*,/)", key="expression")

# Create buttons for basic operations
operators = ["+", "-", "*", "/"]
for operator in operators:
    if st.button(operator, key=operator):
        # Ensure at least one number is provided before calculation
        if num1 is not None and num2 is not None:
            result = calculate(f"{num1} {operator} {num2}")
        else:
            result = None

        if result is not None:
            st.write(f"{num1} {operator} {num2} = {result}")
        else:
            st.error("Invalid expression or division by zero")

# Display the user-entered expression for reference
st.write("Your expression:", user_expr)