Added Input and Output

Author: Saidev

04_Input and Output.md

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+### **Input and Output in Python**
+Python provides simple built-in functions for input and output operations. Let's go over them in detail.
+
+---
+
+### **1. Input in Python**
+The `input()` function is used to take input from the user.
+
+#### **Basic Usage**
+- The `input()` function reads the input as a string.
+  ```python
+  name = input("Enter your name: ")
+  print("Hello, " + name + "!")
+  ```
+
+#### **Converting Input to Other Data Types**
+- Use type-casting functions like `int()`, `float()`, etc., to convert user input.
+  ```python
+  age = int(input("Enter your age: "))
+  print("You are", age, "years old!")
+  ```
+
+#### **Example: Adding Two Numbers**
+```python
+num1 = int(input("Enter first number: "))
+num2 = int(input("Enter second number: "))
+print("The sum is:", num1 + num2)
+```
+
+---
+
+### **2. Output in Python**
+The `print()` function is used to display output to the user.
+
+#### **Basic Usage**
+```python
+print("Hello, World!")
+```
+
+#### **Printing Multiple Values**
+- Separate multiple values with commas. Python automatically inserts a space between them.
+  ```python
+  name = "Alice"
+  age = 25
+  print("Name:", name, "Age:", age)
+  ```
+
+#### **Using String Formatting**
+- **f-strings** (Python 3.6+):
+  ```python
+  name = "Alice"
+  age = 25
+  print(f"My name is {name}, and I am {age} years old.")
+  ```
+
+- **`format()` Method**:
+  ```python
+  print("My name is {}, and I am {} years old.".format(name, age))
+  ```
+
+- **Old-style Formatting (`%` Operator)**:
+  ```python
+  print("My name is %s, and I am %d years old." % (name, age))
+  ```
+
+#### **Changing Separator and End Characters**
+- **`sep` Parameter**: Specifies the separator between values.
+  ```python
+  print("apple", "banana", "cherry", sep=", ")
+  ```
+
+- **`end` Parameter**: Changes the ending character (default is a newline `\n`).
+  ```python
+  print("Hello", end=" ")
+  print("World!")
+  ```
+
+---
+
+### **3. Example Program: Simple Calculator**
+```python
+print("Simple Calculator")
+num1 = float(input("Enter the first number: "))
+num2 = float(input("Enter the second number: "))
+
+print("Choose an operation:")
+print("1. Add")
+print("2. Subtract")
+print("3. Multiply")
+print("4. Divide")
+
+choice = int(input("Enter your choice (1-4): "))
+
+if choice == 1:
+    print("Result:", num1 + num2)
+elif choice == 2:
+    print("Result:", num1 - num2)
+elif choice == 3:
+    print("Result:", num1 * num2)
+elif choice == 4:
+    if num2 != 0:
+        print("Result:", num1 / num2)
+    else:
+        print("Error: Division by zero is not allowed!")
+else:
+    print("Invalid choice.")
+```
+
+---
+
+### **4. Advanced Output Formatting**
+Python provides the `format()` function and formatted string literals for more control.
+
+#### **Controlling Decimal Places**
+- Using `:.nf` (where `n` is the number of decimal places):
+  ```python
+  pi = 3.14159265358979
+  print(f"Pi to 2 decimal places: {pi:.2f}")
+  ```
+
+#### **Padding and Alignment**
+- Left-align, right-align, and center-align using `<`, `>`, and `^`:
+  ```python
+  print(f"{'Name':<10}{'Age':>5}")
+  print(f"{'Alice':<10}{25:>5}")
+  ```
+
+#### **Printing Percentages**
+- Use `:.n%` for percentages:
+  ```python
+  success_rate = 0.857
+  print(f"Success rate: {success_rate:.2%}")
+  ```
+
+---