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Type Conversion in Python: int(), float(), str() and bool() Explained

Have you ever entered a number into a Python program but received an error when trying to perform a calculation? This is a common problem for beginners. It often happens because the data type of a value is different from what the program expects. For example, when you use Python's input() function, the value entered by the user is returned as a string. If you want to perform mathematical calculations with that value, you may need to convert it into a numeric type first. This process is called type conversion . In this article, we will learn what type conversion is, why it is useful, how to convert values using int() , float() , str() , and bool() , and how to avoid common errors. 1. What Is Type Conversion in Python? Type conversion is the process of converting a value from one data type to another. For example, you may convert: A string into an integer. An integer into a floating-point number. A number into a string. A value into a Boolean value. Consider this example: number = ...
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Keywords in Java: A Complete Guide for Beginners

When learning Java, one of the most important concepts you’ll encounter is keywords. Keywords are the reserved words in Java that have a predefined meaning and purpose. They are part of the syntax of the language and cannot be used as identifiers (like variable names, class names, or methods).

For example, words like class, public, static, and void are all keywords in Java.

What Are Keywords in Java?

  • Definition: Keywords are special words that are reserved by the Java language.

  • Purpose: They define the structure and rules of the program.

  • Restriction: You cannot use them as names for variables, methods, or classes.

For example:

int class = 10;   // ❌ Invalid, because 'class' is a keyword
int number = 10;  // ✅ Valid

Characteristics of Java Keywords

  1. All keywords are case-sensitive and must be written in lowercase.

    • Example: Class (with capital C) is not a keyword, but class is.

  2. Keywords are reserved and cannot be redefined.

  3. They define the syntax and structure of Java programs.

List of Java Keywords

Java has 50 keywords (as of Java 17). Here are the most commonly used ones grouped by category:

1. Access Modifiers

  • public, private, protected, default

2. Class, Method, and Object Related

  • class, interface, extends, implements, new, this, super

3. Control Flow

  • if, else, switch, case, default, while, do, for, break, continue, return

4. Data Types

  • int, float, double, char, boolean, byte, short, long, void

5. Exception Handling

  • try, catch, finally, throw, throws

6. Others

  • static, final, abstract, synchronized, volatile, transient, native, package, import

Example Program Using Keywords

Here’s a simple Java program that demonstrates keywords in action:

public class KeywordExample {
    public static void main(String[] args) {
        int number = 10;       // 'int' is a keyword
        if (number > 5) {      // 'if' is a keyword
            System.out.println("Number is greater than 5");
        } else {               // 'else' is a keyword
            System.out.println("Number is 5 or less");
        }
    }
}

Output:

Number is greater than 5

Conclusion

Keywords are the building blocks of Java syntax. They help define the structure of programs and control the flow of execution. As a beginner, understanding and memorizing Java keywords is essential because they form the foundation for writing correct and error-free code.

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