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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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Tokens in Java: A Beginner’s Guide

When learning Java, one of the very first concepts you’ll come across is tokens. Tokens are the smallest building blocks of a Java program. Just like words form a sentence in English, tokens form a program in Java. Without understanding tokens, it’s difficult to understand how a program is written and executed.

What are Tokens in Java?

In Java, a token is the smallest element of a program that has a specific meaning to the compiler. Tokens cannot be divided further and are used to construct statements, expressions, and methods.

For example, in the following line of Java code:

int age = 20;

  • int → Keyword

  • age → Identifier

  • = → Operator

  • 20 → Literal

  • ; → Separator

All these are tokens.

Types of Tokens in Java

Java tokens are categorized into 6 types:

1. Keywords

  • Reserved words in Java that have predefined meanings.

  • Cannot be used as identifiers (variable names, method names, etc.).

  • Example: int, class, public, static, if, else, return.

public class Main {
    public static void main(String[] args) {
        int number = 10; // 'int' and 'public' are keywords
        System.out.println(number);
    }
}

2. Identifiers

  • Names given to variables, methods, classes, etc.

  • Rules: Must start with a letter, $, or _. Cannot start with digits.

  • Example: age, studentName, main.

int age = 25; // 'age' is an identifier

3. Literals (Constants)

  • Fixed values that don’t change during execution.

  • Types of literals:

    • Integer (10, -5)

    • Floating point (3.14, 2.5f)

    • Character ('A')

    • String ("Hello")

    • Boolean (true, false)

double pi = 3.14159; // 3.14159 is a literal

4. Operators

  • Symbols used to perform operations on variables and values.

  • Types:

    • Arithmetic (+, -, *, /, %)

    • Relational (==, !=, >, <, >=, <=)

    • Logical (&&, ||, !)

    • Assignment (=, +=, -=)

    • Unary (++, --)

int x = 10, y = 20;
int sum = x + y; // '+' is an operator

5. Separators (Punctuators)

  • Special symbols used to separate statements and code blocks.

  • Examples:

    • ; (statement terminator)

    • { } (block of code)

    • , (separates variables)

    • () (method parameters)

    • [] (array declaration)

int numbers[] = {1, 2, 3}; // {}, [], , are separators

6. Comments (Not technically tokens, but important)

  • Used to add notes in the program. Ignored by the compiler.

  • Types:

    • Single-line: //

    • Multi-line: /* ... */

    • Documentation: /** ... */

// This is a single-line comment
/* This is 
   a multi-line comment */

Example Program with Tokens

public class TokensExample {
    public static void main(String[] args) {
        int a = 5;        // int, a, =, 5, ; are tokens
        int b = 10;       // int, b, =, 10, ; are tokens
        int sum = a + b;  // int, sum, =, a, +, b, ; are tokens
        System.out.println("Sum: " + sum); // identifiers, literals, operators
    }
}

Output:

Sum: 15

Conclusion

Tokens in Java are the fundamental units of code. By combining keywords, identifiers, literals, operators, and separators, you can write complete and meaningful Java programs. Understanding tokens is essential for beginners, as it lays the foundation for mastering Java programming.

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