Basic Calculator
Basic Calculator
Introduction:
This basic calculator program provides a foundation for more advanced calculator applications, which may include additional features, a graphical user interface (GUI), and error handling for a wider range of scenarios.
This basic calculator program allows the user to perform addition, subtraction, multiplication, and division operations on two numbers. It includes input validation to handle division by zero and provides a simple user interface for continuous calculations until the user decides to exit.
Program in cpp
:
#include <iostream>
using namespace std;
// Function to add two numbers
double add(double x, double y) {
return x + y;
}
// Function to subtract two numbers
double subtract(double x, double y) {
return x  y;
}
// Function to multiply two numbers
double multiply(double x, double y) {
return x * y;
}
// Function to divide two numbers
double divide(double x, double y) {
if (y != 0) {
return x / y;
} else {
cout << "Error: Cannot divide by zero!" << endl;
return 0; // You can customize the return value for division by zero
}
}
int main() {
char operation;
double num1, num2, result;
// Enter operator (+, , *, /): "
cin >> operation;
// Enter first number
cin >> num1;
// Enter second number:
cin >> num2;
switch (operation) {
case '+':
result = add(num1, num2);
break;
case '':
result = subtract(num1, num2);
break;
case '*':
result = multiply(num1, num2);
break;
case '/':
result = divide(num1, num2);
break;
default:
cout << "Error: Invalid operator" << endl;
return 1; // Exit program with an error code
}
cout << result << endl;
return 0;
}
StepByStep Explanation in:
 Header and Namespace:
#include <iostream>
: Includes the necessary header file for input and output operations.using namespace std;
: Avoids the need to usestd::
before standard C++ identifiers.
 Function Declarations:
 Four functions (
add
,subtract
,multiply
, anddivide
) are declared to perform basic arithmetic operations.
 Four functions (
 Function Definitions:
 Each function is defined to implement the corresponding arithmetic operation.
 Main Function:
main()
: The entry point of the program.
 User Input:
 Prompts the user to enter the operator, the first number, and the second number.
 Switch Statement:
 Uses a switch statement to determine the operation to be performed based on the entered operator.
 Perform Calculation:
 Calls the appropriate function to perform the calculation.
 Error Handling:
 Checks for invalid operators and displays an error message.
 Display Result:
 Outputs the result of the calculation.
 Exit Program:
 Returns 0 to indicate successful program execution.
Program in python
:
# Basic Calculator Program
def add(x, y):
"""Addition function"""
return x + y
def subtract(x, y):
"""Subtraction function"""
return x  y
def multiply(x, y):
"""Multiplication function"""
return x * y
def divide(x, y):
"""Division function"""
if y != 0:
return x / y
else:
return "Cannot divide by zero!"
# Main program loop
while True:
# User input
# Enter first number
num1 = float(input())
# Enter operator (+, , *, /)
operator = input()
# Enter second number
num2 = float(input()
# Perform calculation based on the operator
if operator == '+':
result = add(num1, num2)
elif operator == '':
result = subtract(num1, num2)
elif operator == '*':
result = multiply(num1, num2)
elif operator == '/':
result = divide(num1, num2)
else:
result = "Invalid operator"
# Display the result
print(result)
# Ask if the user wants to perform another calculation
another_calculation = input("Do you want to perform another calculation? (yes/no): ").lower()
if another_calculation != 'yes':
break
print("Calculator program terminated.")
This basic calculator program allows the user to perform addition, subtraction, multiplication, and division operations on two numbers. It includes input validation to handle division by zero and provides a simple user interface for continuous calculations until the user decides to exit.
StepByStep Explanation:

User Input:
 The program starts by taking input from the user. In this case, it prompts the user to enter two numbers and an operator (addition, subtraction, multiplication, or division).
num1 = float(input("Enter first number: ")) operator = input("Enter operator (+, , *, /): ") num2 = float(input("Enter second number: "))

Functions for Operations:
 The program defines functions for basic arithmetic operations: addition, subtraction, multiplication, and division.
def add(x, y): return x + y def subtract(x, y): return x  y def multiply(x, y): return x * y def divide(x, y): if y != 0: return x / y else: return "Cannot divide by zero!"

Calculation:
 Based on the user's input, the program performs the corresponding calculation using the defined functions.
if operator == '+': result = add(num1, num2) elif operator == '': result = subtract(num1, num2) elif operator == '*': result = multiply(num1, num2) elif operator == '/': result = divide(num1, num2) else: result = "Invalid operator"

Display Result:
 The program then displays the result of the calculation.
print(f"Result: {result}")

User Interaction Loop:
 The program uses a loop to allow the user to perform multiple calculations without restarting the program.
while True: # ... # Code for calculation and result display # ... another_calculation = input("Do you want to perform another calculation? (yes/no): ").lower() if another_calculation != 'yes': break

Error Handling:
 The division function includes a simple error check to prevent division by zero.
def divide(x, y): if y != 0: return x / y else: return "Cannot divide by zero!"

Termination:
 The program terminates when the user chooses not to perform another calculation.
print("Calculator program terminated.")
Program in java
:
import java.util.Scanner;
public class BasicCalculator {
// Function to add two numbers
public static double add(double x, double y) {
return x + y;
}
// Function to subtract two numbers
public static double subtract(double x, double y) {
return x  y;
}
// Function to multiply two numbers
public static double multiply(double x, double y) {
return x * y;
}
// Function to divide two numbers
public static double divide(double x, double y) {
if (y != 0) {
return x / y;
} else {
System.out.println("Error: Cannot divide by zero!");
return 0; // You can customize the return value for division by zero
}
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
// Step 1: Prompt the user for the operator
// System.out.print("Enter operator (+, , *, /): ");
char operator = scanner.next().charAt(0);
// Step 2: Prompt the user for the first number
// System.out.print("Enter first number: ");
double num1 = scanner.nextDouble();
// Step 3: Prompt the user for the second number
// System.out.print("Enter second number: ");
double num2 = scanner.nextDouble();
double result;
// Step 4: Perform the selected operation using a switch statement
switch (operator) {
case '+':
result = add(num1, num2);
break;
case '':
result = subtract(num1, num2);
break;
case '*':
result = multiply(num1, num2);
break;
case '/':
result = divide(num1, num2);
break;
default:
// Step 5: Handle invalid operator
System.out.println("Error: Invalid operator");
return; // Exit program
}
// Step 6: Display the result
System.out.println(result);
// Step 7: Close the scanner
scanner.close();
}
}
Stepbystep explanation:
 Import Statement:
import java.util.Scanner;
: Imports theScanner
class for user input.
 Function Declarations:
 Four functions (
add
,subtract
,multiply
, anddivide
) are declared to perform basic arithmetic operations.
 Four functions (
 Main Method:
public static void main(String[] args)
: The entry point of the program.
 Scanner Initialization:
Scanner scanner = new Scanner(System.in);
: Creates aScanner
object to read user input.
 User Input:
 Prompts the user to enter the operator, the first number, and the second number.
 Switch Statement:
 Uses a switch statement to determine the operation to be performed based on the entered operator.
 Perform Calculation:
 Calls the appropriate function to perform the calculation.
 Error Handling:
 Checks for invalid operators and displays an error message.
 Display Result:
 Outputs the result of the calculation.
 Close Scanner:
scanner.close();
: Closes the scanner to prevent resource leaks.
This Java program provides a basic structure for a consolebased calculator, allowing the user to perform simple arithmetic calculations.
Time and Space Complexities:
C++:
Time Complexity:
 The time complexity of this basic calculator program is primarily determined by the arithmetic operations. These operations generally have constant time complexity.
 In this case, the arithmetic operations (add, subtract, multiply, divide) are simple and can be considered O(1) or constant time.
Space Complexity:
 The space complexity is also minimal. It mainly involves the storage of variables, input values, and a few function calls.
 The space complexity is O(1), as it doesn't depend on the input size but rather on the fixed number of variables used.
Python:
Time Complexity:
 Similar to C++, the arithmetic operations have constant time complexity.
 Python's arithmetic operations also have constant time complexity, and their implementation is optimized for efficiency.
Space Complexity:
 Python may have a slightly higher space complexity due to its dynamic typing and additional memory required for managing objects.
 The space complexity is still relatively low and can be considered O(1) for the basic calculator program.
Java:
Time Complexity:
 Like C++ and Python, the time complexity is primarily determined by the arithmetic operations, which have constant time complexity.
Space Complexity:
 Java, being a compiled language, has a bit more overhead than Python or C++. It involves managing objects and additional memory for the Java Virtual Machine (JVM).
 The space complexity is still low and considered O(1) for the basic calculator program.
In summary, the time complexity is primarily determined by the arithmetic operations, all of which have constant time complexity. The space complexity is minimal, with O(1) being a reasonable approximation for the basic calculator programs in C++, Python, and Java.
Test Cases

Input:
10

4
Output:
6Explanation: The user inputs the numbers 10 and 4, and the operator . The program should subtract the second number from the first (10  4) and output 6.

Input:
7
*
2
Output:
14
Explanation: The user inputs the numbers 7 and 2, and the operator *. The program should multiply the two numbers (7 * 2) and output 14. 
Input:
12
/
3
Output:
4.0
Explanation: The user inputs the numbers 12 and 3, and the operator /. The program should divide the first number by the second (12 / 3) and output 4.0.