Programming Holes

Front 1

What's the difference between Float, Double, and Decimal?

Back 1

Precision, mainly.

Float: 32 bits
Double: 64 bits
Decimal: 128 bits

Decimal is up to 20x slower in tests, but used for financial mathematical operations because of its greater precision and therefore higher degree of accuracy.

Decimals also allow trailing zeros, where Float and Double cut them off.

Front 2

S in SOLID

Back 2

Single Responsibility

Front 3

O in SOLID

Back 3

Open/Closed Principle

Front 4

L in SOLID

Back 4

Liskov Substitution Principle

Front 5

I in SOLID

Back 5

Interface Segregation

Front 6

D in SOLID

Back 6

Dependency Inversion

Front 7

How do you force a typed number to be float, double, or decimal?

Back 7

The added character trailing the number:

float: 10.02F

double: 10.02D

decimal: 10.02M

Front 8

What's the difference between a CLUSTERED and NONCLUSTERED index?

Back 8

A CLUSTERED index forces the table rows to be physically stored on disk in a particular order. As a result, there can only be one clustered index per table. This will affect write times to the table because the data must be arranged properly according to the index. It can increase the speed of a specific read strategy.

A NONCLUSTERED index is one with pointers to the actual table data. As a result, it does not care how the data is physically stored. This makes it possible to have multiple nonclustered indexes per table.

Front 9

What is Dynamic Typing?

Back 9

The engine figures out the data types of variables during execution, such as JavaScript.

var age = 5;

var pi = 3.14;

Front 10

What is Static Typing?

Back 10

The compiler is told ahead of time in code, the data to be expected for each variable, such as C#, Java, C++, etc.

int age = 5;

double pi = 3.14;

Front 11

What are Primitive Types?

Back 11

Variables whose types represent a single value, that is, not an object.

examples:

5

3.14

"This is a primitive type in JavaScript"

Front 12

What are the Primitive Types in JavaScript?

Back 12

undefined

null

boolean

string

number

symbol (es6)

Front 13

What is Infix Notation?

Back 13

Operators are placed between two parameters (most human readable).

3 + 4

Front 14

What is Prefix Notation?

Back 14

Operators are placed before two parameters.

+ 3 4

Front 15

What is Postfix Notation?

Back 15

Operators are placed after two parameters.

3 4 +

Front 16

What Associativity is the = operator?

(JavaScript, C#, Java)

Back 16

Right-to-left.

var b = 5;

var c = 6;

b = c;

(b equals 6)

Front 17

What Associativity is the * operator?

(JavaScript, C#, Java)

Back 17

Left-to-right.

(3+1) * (3-2)

3+1 will get calculated first, and then 3-2. Then, they will be multiplied together.

Front 18

What is Coercion?

Back 18

Converting a value from one type to another.

JavaScript examples:
-----------------------
var a = 1 + '2';
console.log(a);

output: 12 (1 was coerced to '1').
-----------------------

1 == "1"

output: true (1 was coerced to "1")
-----------------------
console.log(3 < 2 < 1);

output: true (< is Left-to-Right precedence, 3 < 2 is false, then false < 1 is true, because false is coerced to 0).

Front 19

What is NaN in JavaScript?

Back 19

Not-A-Number

kind of a primitive type, it results in an unsuccessful coercion operation.

Front 20

In JavaScript, what's the difference between the operators == and ===?

Back 20

== is the Equality operator. It will coerce the values on either side of it if needed before comparing.


=== is the Strict Equality operator. It does not try to coerce the values on each side of it. Strictly checks equality of the same type.

Front 21

How do you set a default value for a variable in JavaScript (prior to ecma6)?

Back 21

function greet(name) {

name = name || "Bob";

console.log(name);

}

This works because || returns true/false, yes, but it will return the value itself that equates to true, not just true/false.

Front 22

What is Computed Member Access in JavaScript?

Back 22

var person = new Object();

person["firstname"] = "David";

(The [ and ] on an object, accessing the referenced value)

Front 23

What is the Member Access operator in JavaScript?

Back 23

The dot after an object:

person.firstname;

The dot is a built in operator that accesses properties/functions on an object.

Front 24

Object Literal in JavaScript

Back 24

A shorthand version of new Object() denoted by {}.

var person = {};

Front 25

First Class Functions (JavaScript)

Back 25

Everything you can do with other types, you can also do with functions.

i.e. assign them to variables, pass them around, create them on the fly.

Front 26

What does mutable mean?

Back 26

Can be changed:

var a = 5;

a = 4;

Front 27

What does immutable mean?

Back 27

Cannot be changed:

public const int age = 5;

age = 4; <--- not allowed, constant

Front 28

What is Aspect-Oriented Programming (AOP)?

Back 28

A programming paradigm that aims to increase modularity by allowing the separation of crosscutting concerns.

Front 29

What is an example of a crosscutting concern?

Back 29

Logging, for example. It does not apply to a particular layer, it applies to the whole application.