online compiler and debugger for c/c++

CALULATOR PROGRAM: XML FILE:- <?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <Button android:id="@+id/add" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="19dp" android:text="add" android:textSize="10dp" app:layout_constraintStart_toStartOf="@+id/div" app:layout_constraintTop_toBottomOf="@+id/div" /> <TextView android:id="@+id/ans" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="25dp" android:text="ANSWER" android:textSize="30dp" app:layout_constraintStart_toEndOf="@+id/add" app:layout_constraintTop_toBottomOf="@+id/add" /> <Button android:id="@+id/sub" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="75dp" android:layout_marginRight="75dp" android:layout_marginBottom="25dp" android:text="subtract" android:textSize="10dp" app:layout_constraintBottom_toTopOf="@+id/ans" app:layout_constraintEnd_toEndOf="@+id/sn" /> <Button android:id="@+id/multi" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginBottom="19dp" android:text="multiply" android:textSize="10dp" app:layout_constraintBottom_toTopOf="@+id/sub" app:layout_constraintStart_toStartOf="@+id/sub" /> <Button android:id="@+id/div" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="48dp" android:layout_marginLeft="48dp" android:layout_marginEnd="51dp" android:layout_marginRight="51dp" android:layout_marginBottom="316dp" android:text="Divide" android:textSize="10dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toStartOf="@+id/multi" app:layout_constraintStart_toStartOf="parent" /> <TextView android:id="@+id/tfn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="36dp" android:layout_marginLeft="36dp" android:layout_marginTop="195dp" android:layout_marginBottom="193dp" android:text="FIRST NUMBER" android:textSize="20dp" app:layout_constraintBottom_toBottomOf="@+id/div" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <EditText android:id="@+id/fn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="30dp" android:layout_marginLeft="30dp" android:hint="FIRST NUMBER" android:inputType="number" app:layout_constraintBaseline_toBaselineOf="@+id/tfn" app:layout_constraintStart_toEndOf="@+id/tfn" /> <EditText android:id="@+id/sn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="60dp" android:layout_marginRight="60dp" android:layout_marginBottom="24dp" android:hint="SECOND NUMBER" android:inputType="number" app:layout_constraintBottom_toTopOf="@+id/multi" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toEndOf="@+id/tsn" /> <TextView android:id="@+id/tsn" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginStart="27dp" android:layout_marginLeft="27dp" android:layout_marginEnd="2dp" android:layout_marginRight="2dp" android:text="SECOND NUMBER" android:textSize="20dp" app:layout_constraintBottom_toBottomOf="@+id/sn" app:layout_constraintEnd_toStartOf="@+id/sn" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="@+id/sn" /> </androidx.constraintlayout.widget.ConstraintLayout> ======================================================================================================================== JAVA FILE:- package com.example.main_q18; import androidx.appcompat.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.EditText; import android.widget.TextView; import android.widget.Button; public class MainActivity extends AppCompatActivity { EditText e1,e2; TextView t1; Button b1,b2,b3,b4; double ans; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); e1=findViewById(R.id.fn); e2=findViewById(R.id.sn); t1=findViewById(R.id.ans); b1=(Button) findViewById(R.id.add); b2=(Button) findViewById(R.id.sub); b3=(Button) findViewById(R.id.multi); b4=(Button) findViewById(R.id.div); b1.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Double e=Double.parseDouble(e1.getText().toString()); Double f=Double.parseDouble(e2.getText().toString()); ans=e+f; String ans1=String.valueOf(ans); t1.setText(ans1); ans=0; } }); b2.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Double e=Double.parseDouble(e1.getText().toString()); Double f=Double.parseDouble(e2.getText().toString()); ans=e-f; String ans1=String.valueOf(ans); t1.setText(ans1); ans=0; } }); b3.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Double e=Double.parseDouble(e1.getText().toString()); Double f=Double.parseDouble(e2.getText().toString()); ans=e*f; String ans1=String.valueOf(ans); t1.setText(ans1); ans=0; } }); b4.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Double e=Double.parseDouble(e1.getText().toString()); Double f=Double.parseDouble(e2.getText().toString()); ans=e/f; String ans1=String.valueOf(ans); t1.setText(ans1); ans=0; } }); } } ==================================================================================================