Create app.py

app.py

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+import streamlit as st
+
+# Define backend functions for calculations
+def add(a, b):
+    return a + b
+
+def subtract(a, b):
+    return a - b
+
+def multiply(a, b):
+    return a * b
+
+def divide(a, b):
+    if b != 0:
+        return a / b
+    else:
+        return "Error! Division by zero."
+
+# Streamlit frontend
+st.title("Simple Calculator")
+
+st.write("Choose operation:")
+operation = st.selectbox("Operation", ("Add", "Subtract", "Multiply", "Divide"))
+
+num1 = st.number_input("Enter first number", value=0.0, format="%f")
+num2 = st.number_input("Enter second number", value=0.0, format="%f")
+
+if st.button("Calculate"):
+    if operation == "Add":
+        result = add(num1, num2)
+    elif operation == "Subtract":
+        result = subtract(num1, num2)
+    elif operation == "Multiply":
+        result = multiply(num1, num2)
+    elif operation == "Divide":
+        result = divide(num1, num2)
+
+    st.write(f"Result: {result}")
+