New Programming Languages Tour

Let’s learn programming in multi-lang mode. Since all languages are trying to express same things just in different grammars.

中文Python语法基础

Main method

```Java
    public void main(String[] args) {
        System.out.println("Hello, World!");
    }
```

```Kotlin
    fun main(args: Array<String>) {
        println("Hello, World!")
    }
```

```Swift
    func main() {
        print("Hello, World!")
    }
```

```Python
    def method():
        print("Hello, Main!")
    
    if __name__ == "__main__":
        method()
    elif __name__ == "module_name":
        print("Hello, Module!")
```

Data Types

```Java
    // Primitive Integer Types
    byte byteNumber = 10;           // 1 byte/8-bit signed integer, range from -128 to 127
    short shortNumber = 10;         // 2 bytes/16-bit signed integer, range from -32,768 to 32,767
    int integerNumber = 10;         // 4 bytes/32-bit signed integer, range from -2^31 to 2^31-1
    long longNumber = 1000000000L;  // 8 bytes/64-bit signed integer, range from -2^63 to 2^63-1
    
    // Primitive Floating point Types
    float floatNumber = 10.0f;          // 4 bytes/32-bit floating point number, 6-7 decimal digits
    double doubleNumber = 10.0d;        // 8 bytes/64-bit floating point number, 15 decimal digits
    float scientificNotation = 35e3f;   // 35.0 x 10^3
    double scientificNotation = 12E4;   // 12.0 x 10^4
    
    // Primitive Boolean Types
    boolean isTrue = true;          // 1-bit true/false value
    
    // Primitive Character Types
    char character = 'a';           // 2 bytes/16-bit Unicode character
    char myLetter = 66;             // ASCII value for 'B'
    
    // Reference Types - String 
    String string = "Hello, World!";

    // Reference Types - Arrays
    List<String> list = new ArrayList<>();
    Set<String> set = new HashSet<>();
    Map<String, String> map = new HashMap<>();
    Collection<String> collection = Collections.emptyList();

    // Reference Types - Classes/Objects
    CustomObject customObject = new CustomObject();
```

```Kotlin
    // Number Integer Types
    val byteNumber: Byte = 10               // 1 byte/8-bit signed integer, range from -128 to 127
    val shortNumber: Short = 10             // 2 bytes/16-bit signed integer, range from -32,768 to 32,767
    val integerNumber: Int = 10             // 4 bytes/32-bit signed integer, range from -2^31 to 2^31-1
    val longNumber: Long = 1_000_000_000L   // 8 bytes/64-bit signed integer, range from -2^63 to 2^63-1
    // You can miss type declaration and let Kotlin infer the type
    val myMaxInt = 2_147_483_647            // type inferred as Int
    val myLong = 2_147_483_648              // type inferred as Long
    
    // Number Floating point Types
    val floatNumber: Float = 10.0f      // 4 bytes/32-bit floating point number, 6-7 decimal digits
    val doubleNumber: Double = 10.0     // 8 bytes/64-bit floating point number, 15 decimal digits
    val myFloat = 35E3F                 // 35.0 x 10^3
    val myDouble = 12E4                 // 12.0 x 10^4
    
    // Boolean Types
    val isTrue: Boolean = true          // 1-bit true/false value
    
    // Char Types
    val character: Char = 'a'           // 2 bytes/16-bit Unicode character
    //val myLetter: Char = 66           // Error: Kotlin doesn't support ASCII values for char
    
    // Strings Types
    val string: String = "Hello, World!"
    // String length
    val length = string.length
    // Accessing characters
    val firstChar = string[0]
    // Modifying strings
    //string[0] = 'h'                   // Error: Strings are immutable in Kotlin
    
    // Arrays Types
    var intArray = intArrayOf(1, 2, 3, 4, 5)
    var longArray = longArrayOf(1L, 2L, 3L, 4L, 5L)
    var floatArray = floatArrayOf(1.1f, 2.2f, 3.3f, 4.4f, 5.5f)
    var doubleArray = doubleArrayOf(1.1, 2.2, 3.3, 4.4, 5.5)
    var booleanArray = booleanArrayOf(true, false, true)
    var charArray = charArrayOf('a', 'b', 'c')
    var stringArray = arrayOf("Hello", "World")
    // Array size
    var size = stringArray.size
    // Accessing elements
    var element = stringArray[0]
    // Modifying elements
    stringArray[0] = "Hi"

    // Collections Types
    val list: List<String> = listOf()
    var set: Set<String> = mutableSetOf()
    var map: Map<String, String> = mapOf("key" to "value")
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

Operators & Maths

```
```Java
    var_dump('hello');
```
```

```Kotlin
    console.log('hello');
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

If-Else

```
```Java
    var_dump('hello');
```
```

```Kotlin
    console.log('hello');
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

Switch

```
```Java
    var_dump('hello');
```
```

```Kotlin
    console.log('hello');
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

For Loop

```
```Java
    var_dump('hello');
```
```

```Kotlin
    console.log('hello');
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

While Loop

```
```Java
    var_dump('hello');
```
```

```Kotlin
    console.log('hello');
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

Functions/Methods

```
```Java
    var_dump('hello');
```
```

```Kotlin
    console.log('hello');
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

Lambda

```
```Java
    var_dump('hello');
```
```

```Kotlin
    console.log('hello');
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

Classes/Objects

```
```Java
    var_dump('hello');
```
```

```Kotlin
    console.log('hello');
```

```
```Swift
    pputs 'hello'
```
```
```
```Python
    print('hello')
```
```

New Programming Languages Tour

Main method

Data Types

Operators & Maths

If-Else

Switch

For Loop

While Loop

Functions/Methods

Lambda

Classes/Objects

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Written by Cui Follow