Moeer/streamlit-calculator

1import streamlit as st2import math3import re4 5# Session state for history6if 'history' not in st.session_state:7    st.session_state.history = []8 9# Title and description10st.title("🧮 Multi-Mode Calculator")11st.markdown("Switch between different calculator modes using the tabs below.")12 13# Helper function for safe evaluation14def safe_eval(expr, mode):15    try:16        # Only allow math functions in scientific mode17        allowed_names = {18            **{k: v for k, v in math.__dict__.items() if not k.startswith("__")},19            "abs": abs,20            "round": round21        } if mode == "Scientific" else {}22        return eval(expr, {"__builtins__": {}}, allowed_names)23    except Exception as e:24        return f"Error: {e}"25 26# Tabs for calculator modes27tab1, tab2, tab3, tab4 = st.tabs(["Basic", "Scientific", "Programmer", "Custom"])28 29with tab1:30    st.subheader("🧾 Basic Calculator")31    num1 = st.number_input("First number", key="basic_num1")32    num2 = st.number_input("Second number", key="basic_num2")33    operation = st.selectbox("Operation", ["Add", "Subtract", "Multiply", "Divide"])34    35    if st.button("Calculate", key="basic_calc"):36        with st.spinner("Calculating..."):37            if operation == "Add":38                result = num1 + num239            elif operation == "Subtract":40                result = num1 - num241            elif operation == "Multiply":42                result = num1 * num243            elif operation == "Divide":44                result = "Error: Division by zero" if num2 == 0 else num1 / num245            st.session_state.history.append(f"{num1} {operation} {num2} = {result}")46            st.success(f"Result: {result}")47 48with tab2:49    st.subheader("📐 Scientific Calculator")50    expr = st.text_input("Enter expression (e.g., sin(1), log(10), 2**3)", key="sci_expr")51 52    if expr:53        with st.spinner("Evaluating..."):54            result = safe_eval(expr, mode="Scientific")55            st.session_state.history.append(f"{expr} = {result}")56            if isinstance(result, str) and result.startswith("Error"):57                st.error(result)58            else:59                st.success(f"Result: {result}")60 61with tab3:62    st.subheader("🧑‍💻 Programmer Calculator")63    number = st.text_input("Enter number", key="prog_input")64    base = st.selectbox("Convert from", ["Binary", "Decimal", "Hexadecimal"])65 66    def convert_programmer(num_str, base):67        try:68            if base == "Binary":69                dec = int(num_str, 2)70            elif base == "Hexadecimal":71                dec = int(num_str, 16)72            else:73                dec = int(num_str)74            return {75                "Binary": bin(dec),76                "Decimal": dec,77                "Hexadecimal": hex(dec)78            }79        except ValueError:80            return {"Error": "Invalid number format."}81 82    if number:83        with st.spinner("Converting..."):84            result = convert_programmer(number, base)85            if "Error" in result:86                st.error(result["Error"])87            else:88                st.session_state.history.append(f"{number} ({base}) => {result}")89                st.code(result, language="json")90 91with tab4:92    st.subheader("🧩 Custom Mode")93    st.markdown("Input any mathematical formula using standard Python syntax.")94    user_expr = st.text_area("Formula input", placeholder="e.g., 3 * (2 + 5) / sqrt(9)")95 96    if user_expr:97        with st.spinner("Processing..."):98            result = safe_eval(user_expr, mode="Scientific")99            st.session_state.history.append(f"{user_expr} = {result}")100            if isinstance(result, str) and result.startswith("Error"):101                st.error(result)102            else:103                st.success(f"Result: {result}")104 105# Calculation History106with st.expander("📜 Calculation History"):107    for entry in st.session_state.history:108        st.write(entry)109    if st.button("Clear History"):110        st.session_state.history.clear()111        st.success("History cleared.")112 113# Footer114st.caption("🔹 Built with Streamlit — Responsive and lightweight calculator app.")115