Common lines of code in different languages for quick reference and comparison: Java, JavaScript, Objective-C, Python, Ruby, Scala, Swift.

• Intro
• Basic things to consider
• Variable declaration
• Function calls, property access, print things
• String manipulation
• More to do...

This document shows common code constructions in different languages (for now, those that I use more frequently). One purpose is to serve as a quick reference when you need to switch languages and you don't know or remember basic things. Another use is to see languages side by side, to compare their differences and similarities.

If you see something that could be improved, added or fixed please let me know. I will gladly consider your suggestions.

Back to top

Objective-C and Swift Always import Foundation, or UIKit if using view classes:

@import UIKit;   // Objective-C

import UIKit     // Swift

Back to top

Basic variable for some common types (numbers, strings, booleans). Here you can also see name conventions (camelCase, snake_case) and line comments.

Java

int age = 18;
final String name = "John Smith"; // Constant (final)
double height = 1.75;
boolean hasChildren = false;

JavaScript

var age = 18;
var name = "John Smith";  // Also with ''
var height = 1.75;
var hasChildren = false;

Objective-C

int age = 18;
NSString* name = @"John Smith";
double height = 1.75;
BOOL hasChildren = NO; // also `false`

Python

age = 18
name = 'John Smith'
height = 1.75
has_children = False

Ruby

age = 18
name = 'John Smith'  # With "" you can interpolate
height = 1.75
has_children = false

Scala

var age = 18
val name = "John Smith"     // Constant (val)
var height : Double = 1.75  // Explicit type is optional
var hasChildren = false

Swift

var age = 18
let name = "John Smith"     // Constant (let)
var height : Double = 1.75  // Explicit type is optional
var hasChildren = false

Back to top

Basic usage of functions, properties, and how to print messages on screen/console. I added this section as an introduction for the following ones.

Java

User user = database.find(email, pwd);          // Call function
System.out.println("Hello " + user.getName());  // Print property

JavaScript

var user = database.find(email, pwd);  // Call function
console.log("Hello " + user.name);     // Print property

Objective-C

User* user = [database find:email pass:pwd];    // Call function
NSLog(@"Hello %@", user.name); // Print property

Python

user = database.find(email, pwd)  # Call function
print "Hello " + user.name        # Print property

Ruby

user = database.find(email, pwd)  # Call function
puts "Hello #{user.name}"         # Print property

Scala

val user = database.find(email, pwd)  // Call function
println("Hello " + user.name)         // Print property

Swift

let user = database.find(email, pass:pwd)  // Call function
print("Hello \(user.name)")                             // Print property

Back to top

Java

int length = name.length();             // Length
String text = name + " is " + age;  // Concatenate
boolean b = name.contains("Smith");     // Find
b = name.indexOf("Smith") >= 0;         // Index
String first = name.substring(0, 4);    // Substring
String[] parts = text.split(" ");       // Split

JavaScript

var length = name.length();          // Length
var text = name + " is " + age;  // Concatenate
var b = name.indexOf("Smith") >= 0;  // Find/Index
var first = name.substring(0, 4);    // Substring
var parts = text.split(" ");         // Split

Objective-C

int lenght = [name length];                                     // Length
NSString* text = [NSString stringWithFormat:
  @"%@ is %@", name, @(age)];                                  // Interpolate
text = [text stringByAppendingString:@" years old"];           // Concatenate
BOOL b = [name rangeOfString:@"Smith"].location != NSNotFound;  // Find/Index
NSString* first = [name substringToIndex:4];                    // Substring
NSString* last = [name substringWithRange:NSMakeRange(5, 10)];  // Substring
NSArray<NSString*>* parts = [text componentsSeparatedByString:@" "]; // Split

Python

length = len(name)                # length
text = name + " is " + str(age)     # Concatenate
found = "Smith" in name           # Find
found = name.find(" ") >= 0       # Index
first_name = name[0:index]        # Substring
parts = text.split(" ")           # Split

Ruby

length = name.length                    # length
text = "#{name} is #{age}"          # Interpolate
text += ", height: " + height                 # Concatenate
found = name.include? "Smith"           # Find
index = name.index(" ")                 # Index (truthy if found)
first_name = name[0...4]                # Substring
parts = text.split(" ")                 # Split

Scala

var text = s"$name is $age"        // Interpolate
text += ", height: " + height                // Concatenate
var found = name.contains("Smith")     // Find
found = name.indexOf(" ") >= 0         // Index
val firstName = name.substring(0, 4)   // Substring
val parts = text.split(" ")            // Split

Swift

int length = name.length                   // Length
var text = "\(name) is \(age)"         // Interpolate
text = String(format: "%@ is %@", name, age)
text += ", height: " + height                    // Concatenate
let range = string.rangeOfString("Smith")  // Index
let found = range != nil                   // Find
// Try: http://stackoverflow.com/a/24046551/1121497
let parts = text.componentsSeparatedByString(" ")   // Split

Back to top

Java

JavaScript

Objective-C

Python

Ruby

Scala

Swift

Back to top