Create app.py

app.py

@@ -0,0 +1,140 @@
+import streamlit as st
+import math
+import pandas as pd
+
+st.set_page_config(page_title="Mobile Calculator", page_icon="🧮", layout="centered")
+
+# ---------------- SESSION STATE ----------------
+if "expression" not in st.session_state:
+    st.session_state.expression = ""
+
+if "history" not in st.session_state:
+    st.session_state.history = []
+
+# ---------------- SAFE EVAL ----------------
+def safe_eval(expr):
+    allowed = {
+        "sqrt": math.sqrt,
+        "sin": math.sin,
+        "cos": math.cos,
+        "tan": math.tan,
+        "log": math.log10,
+        "pi": math.pi,
+        "e": math.e
+    }
+    try:
+        return eval(expr, {"__builtins__": None}, allowed)
+    except:
+        return "Error"
+
+# ---------------- STYLE ----------------
+st.markdown("""
+<style>
+body {background-color:#0f172a;}
+.display {
+    background:#1e293b;
+    color:white;
+    padding:20px;
+    border-radius:20px;
+    font-size:32px;
+    text-align:right;
+    margin-bottom:15px;
+}
+.stButton>button {
+    height:65px;
+    border-radius:20px;
+    font-size:22px;
+    font-weight:bold;
+}
+</style>
+""", unsafe_allow_html=True)
+
+st.title("🧮 Advanced Mobile Calculator")
+
+# ---------------- DISPLAY ----------------
+st.markdown(f"<div class='display'>{st.session_state.expression or '0'}</div>", unsafe_allow_html=True)
+
+if st.session_state.expression:
+    st.write("Result:", safe_eval(st.session_state.expression))
+
+# ---------------- BUTTON FUNCTIONS ----------------
+def add(val):
+    st.session_state.expression += str(val)
+
+def clear():
+    st.session_state.expression = ""
+
+def delete():
+    st.session_state.expression = st.session_state.expression[:-1]
+
+def calculate():
+    result = safe_eval(st.session_state.expression)
+    st.session_state.history.append(f"{st.session_state.expression} = {result}")
+    st.session_state.expression = str(result)
+
+# ---------------- FIXED MOBILE GRID ----------------
+layout = [
+    ["C", "DEL", "(", ")"],
+    ["7", "8", "9", "/"],
+    ["4", "5", "6", "*"],
+    ["1", "2", "3", "-"],
+    ["0", ".", "+", "="],
+]
+
+for r, row in enumerate(layout):
+    cols = st.columns(4)
+    for c, button in enumerate(row):
+
+        key_name = f"btn_{r}_{c}"
+
+        if button == "C":
+            cols[c].button(button, key=key_name, on_click=clear)
+
+        elif button == "DEL":
+            cols[c].button(button, key=key_name, on_click=delete)
+
+        elif button == "=":
+            cols[c].button(button, key=key_name, on_click=calculate)
+
+        else:
+            cols[c].button(
+                button,
+                key=key_name,
+                on_click=add,
+                args=(button,)
+            )
+
+st.markdown("---")
+
+# ---------------- SCIENTIFIC BUTTONS ----------------
+st.subheader("Scientific")
+
+sci_buttons = ["sqrt(", "sin(", "cos(", "tan(", "log(", "pi", "e"]
+
+cols = st.columns(len(sci_buttons))
+
+for i, btn in enumerate(sci_buttons):
+    cols[i].button(
+        btn,
+        key=f"sci_{i}",
+        on_click=add,
+        args=(btn,)
+    )
+
+st.markdown("---")
+
+# ---------------- HISTORY ----------------
+st.subheader("History")
+
+if st.session_state.history:
+    for item in reversed(st.session_state.history):
+        st.write(item)
+
+    df = pd.DataFrame(st.session_state.history, columns=["Calculations"])
+    st.download_button(
+        "Download History",
+        df.to_csv(index=False),
+        file_name="history.csv"
+    )
+else:
+    st.info("No calculations yet.")