Tutorial by Examples: bst

string helloWorld = "Hello World!"; string world = helloWorld.Substring(6); //world = "World!" string hello = helloWorld.Substring(0,5); // hello = "Hello" Substring returns the string up from a given index, or between two indexes (both inclusive).

Unlike interfaces, which can be described as contracts for implementation, abstract classes act as contracts for extension. An abstract class cannot be instantiated, it must be extended and the resulting class (or derived class) can then be instantiated. Abstract classes are used to provide generi...

An abstract class is a class marked with the abstract keyword. It, contrary to non-abstract class, may contain abstract - implementation-less - methods. It is, however, valid to create an abstract class without abstract methods. An abstract class cannot be instantiated. It can be sub-classed (exten...

String s = "this is an example"; String a = s.substring(11); // a will hold the string starting at character 11 until the end ("example") String b = s.substring(5, 10); // b will hold the string starting at character 5 and ending right before character 10 ("is an") S...

Operands of the abstract equality operator are compared after being converted to a common type. How this conversion happens is based on the specification of the operator: Specification for the == operator: 7.2.13 Abstract Equality Comparison The comparison x == y, where x and y are values, prod...

Python's str type also has a method for replacing occurences of one sub-string with another sub-string in a given string. For more demanding cases, one can use re.sub. str.replace(old, new[, count]): str.replace takes two arguments old and new containing the old sub-string which is to be replace...

One method is available for counting the number of occurrences of a sub-string in another string, str.count. str.count(sub[, start[, end]]) str.count returns an int indicating the number of non-overlapping occurrences of the sub-string sub in another string. The optional arguments start and end ...

astring = 'thisisashorttext' astring.count('t') # Out: 4 This works even for substrings longer than one character: astring.count('th') # Out: 1 astring.count('is') # Out: 2 astring.count('text') # Out: 1 which would not be possible with collections.Counter which only counts single char...

var='0123456789abcdef' # Define a zero-based offset $ printf '%s\n' "${var:3}" 3456789abcdef # Offset and length of substring $ printf '%s\n' "${var:3:4}" 3456 4.2 # Negative length counts from the end of the string $ printf '%s\n' "${var:3:-5}" 3456789a...

The Problem The abstract equality and inequality operators (== and !=) convert their operands if the operand types do not match. This type coercion is a common source of confusion about the results of these operators, in particular, these operators aren't always transitive as one would expect. &...

See full documentation on LIKE operator. This example uses the Employees Table from the Example Databases. SELECT * FROM Employees WHERE FName LIKE 'John' This query will only return Employee #1 whose first name matches 'John' exactly. SELECT * FROM Employees WHERE FName like 'John%' Ad...

Variable substitutions should only be used inside double quotes. calculation='2 * 3' echo "$calculation" # prints 2 * 3 echo $calculation # prints 2, the list of files in the current directory, and 3 echo "$(($calculation))" # prints 6 Outside of doubl...

A class marked with the keyword abstract cannot be instantiated. A class must be marked as abstract if it contains abstract members or if it inherits abstract members that it doesn't implement. A class may be marked as abstract even if no abstract members are involved. Abstract classes are usually...

Substitutability is a principle in object-oriented programming introduced by Barbara Liskov in a 1987 conference keynote stating that, if class B is a subclass of class A, then wherever A is expected, B can be used instead: class A {...} class B extends A {...} public void method(A obj) {...} ...

Enums can define abstract methods, which each enum member is required to implement. enum Action { DODGE { public boolean execute(Player player) { return player.isAttacking(); } }, ATTACK { public boolean execute(Player player) { re...

Variables inside single quotes ' don't get expanded by POSIX compatible shells, so using a shell variable in a sed substitution requires the use of double quotes " instead of single quotes ': $ var="he" $ echo "hello" | sed "s/$var/XX/" XXllo $ var="he&q...

Syntax is: SUBSTRING ( string_expression, start, length ). Note that SQL strings are 1-indexed. SELECT SUBSTRING('Hello', 1, 2) --returns 'He' SELECT SUBSTRING('Hello', 3, 3) --returns 'llo' This is often used in conjunction with the LEN() function to get the last n characters of a string of un...

To search if a String contains a substring, do the following: NSString *myString = @"This is for checking substrings"; NSString *subString = @"checking"; BOOL doesContainSubstring = [myString containsString:subString]; // YES If targeting iOS 7 or OS X 10.9 (or earlier)...

Implementations in classes, including abstract declarations, take precedence over all interface defaults. Abstract class method takes precedence over Interface Default Method. public interface Swim { default void backStroke() { System.out.println("Swim.backStroke"); ...

# example data test_sentences <- c("The quick brown fox quickly", "jumps over the lazy dog") Let's make the brown fox red: sub("brown","red", test_sentences) #[1] "The quick red fox quickly" "jumps over the lazy dog" Now, ...