Tutorial by Examples: o

Type the following code into your terminal, then press Enter: echo "Hello World" This will produce the following output: Hello World

Exponentiation can be used by using the builtin pow-function or the ** operator: 2 ** 3 # 8 pow(2, 3) # 8 For most (all in Python 2.x) arithmetic operations the result's type will be that of the wider operand. This is not true for **; the following cases are exceptions from this rule: B...

The math-module contains another math.pow() function. The difference to the builtin pow()-function or ** operator is that the result is always a float: import math math.pow(2, 2) # 4.0 math.pow(-2., 2) # 4.0 Which excludes computations with complex inputs: math.pow(2, 2+0j) TypeErro...

Both the math and cmath-module contain the Euler number: e and using it with the builtin pow()-function or **-operator works mostly like math.exp(): import math math.e ** 2 # 7.3890560989306495 math.exp(2) # 7.38905609893065 import cmath cmath.e ** 2 # 7.3890560989306495 cmath.exp(2) # (...

The math module contains the expm1()-function that can compute the expression math.e ** x - 1 for very small x with higher precision than math.exp(x) or cmath.exp(x) would allow: import math print(math.e ** 1e-3 - 1) # 0.0010005001667083846 print(math.exp(1e-3) - 1) # 0.0010005001667083846 p...

Supposing you have a class that stores purely integer values: class Integer(object): def __init__(self, value): self.value = int(value) # Cast to an integer def __repr__(self): return '{cls}({val})'.format(cls=self.__class__.__name__, ...

Click the Run button in the toolbar (or press ⌘R) to build & run your project. Click Stop (or press ⌘.) to stop execution.   Click & hold to see the other actions, Test (⌘U), Profile (⌘I), and Analyze (⇧⌘B). Hold down modifier keys ⌥ option, ⇧ shift, and ⌃ control for more variants.  ...

A submodule references a specific commit in another repository. To check out the exact state that is referenced for all submodules, run git submodule update --recursive Sometimes instead of using the state that is referenced you want to update to your local checkout to the latest state of that s...

You can have multiple versions of Xcode installed at the same time (including beta versions). Simply rename the application in Finder to avoid conflicts. Note: Installing Xcode from the App Store will tend to overwrite an existing version on your machine. You can also install Xcode from a direct ...

CREATE TABLE HR_EMPLOYEES ( PersonID int, LastName VARCHAR(30), FirstName VARCHAR(30), Position VARCHAR(30) ); CREATE TABLE FINANCE_EMPLOYEES ( PersonID INT, LastName VARCHAR(30), FirstName VARCHAR(30), Position VARCHAR(30) ); Let's say we want to ...

String also have an index method but also more advanced options and the additional str.find. For both of these there is a complementary reversed method. astring = 'Hello on StackOverflow' astring.index('o') # 4 astring.rindex('o') # 20 astring.find('o') # 4 astring.rfind('o') # 20 The ...

All built-in collections in Python implement a way to check element membership using in. List alist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] 5 in alist # True 10 in alist # False Tuple atuple = ('0', '1', '2', '3', '4') 4 in atuple # False '4' in atuple # True String astring = 'i am a s...

dict have no builtin method for searching a value or key because dictionaries are unordered. You can create a function that gets the key (or keys) for a specified value: def getKeysForValue(dictionary, value): foundkeys = [] for keys in dictionary: if dictionary[key] == value: ...

Sorted sequences allow the use of faster searching algorithms: bisect.bisect_left()1: import bisect def index_sorted(sorted_seq, value): """Locate the leftmost value exactly equal to x or raise a ValueError""" i = bisect.bisect_left(sorted_seq, value) ...

Let's look at a more complex example that contains a one-to-many relationship. Our query will now contain multiple rows containing duplicate data and we will need to handle this. We do this with a lookup in a closure. The query changes slightly as do the example classes. IdNameBornCountryIdCountry...

Sometimes the number of types you are mapping exceeds the 7 provided by the Func<> that does the construction. Instead of using the Query<> with the generic type argument inputs, we will provide the types to map to as an array, followed by the mapping function. Other than the initial ma...

If the query column names do not match your classes you can setup mappings for types. This example demonstrates mapping using System.Data.Linq.Mapping.ColumnAttributeas well as a custom mapping. The mappings only need to be setup once per type so set them on application startup or somewhere else ...

First, install a version of Microsoft Visual Studio, including the free Community edition. Then, create a Visual Basic Console Application project of type Console Application, and the following code will print the string 'Hello World' to the Console: Module Module1 Sub Main() Consol...

To check the equality of Date values: var date1 = new Date(); var date2 = new Date(date1.valueOf() + 10); console.log(date1.valueOf() === date2.valueOf()); Sample output: false Note that you must use valueOf() or getTime() to compare the values of Date objects because the equality operato...

Using the Cars Table, we will calculate the total, max, min and average amount of money each costumer spent and haw many times (COUNT) she brought a car for repairing. Id CustomerId MechanicId Model Status Total Cost SELECT CustomerId, SUM(TotalCost) OVER(PARTITION BY Cust...