Programming for everybody

Type Conversion In Python, it's impossible to complete certain operations due to the types involved. For instance, you can't add two strings containing the numbers 2 and 3 together to produce the  integer  5, as the operation will be performed on strings, making the result '23'. The solution to this is  type conversion . In that example, you would use the  int  function . Type Conversion !! Another example of type conversion is turning user input (which is a  string ) to numbers ( integers  or  floats ), to allow for the performance of calculations. >>> float (input("Enter a number: ")) + float (input("Enter another number: ")) Enter a number: 40 Enter another number: 2 42.0 Passing non- integer  or  float  values will cause an error. >>> "2" + "3" '23' >>> int ("2") + int ("3") 5 In Python, the types we have used so far have been  integers ,  floats , and  strings ....

Strings If you want to use text in Python, you have to use a  string . A  string   is created by entering text between  two single or double quotation marks . When the Python console displays a  string , it generally uses single quotes. The delimiter used for a  string  doesn't affect how it behaves in any way. >>> "Python is fun!" 'Python is fun!' >>> 'Always look on the bright side of life' 'Always look on the bright side of life' Newlines !! Python provides an easy way to avoid manually writing "\n" to escape newlines in a  string . Create a  string  with  three sets of quotes , and newlines that are created by pressing Enter are automatically escaped for you. >>> """ Customer: Good morning. Owner: Good morning, Sir. Welcome to the National Cheese Emporium. """ 'Customer: Good morning. \n Owner: Good morning, Sir. Welcome to the National Cheese Emporium.' There is a...

Exponentiation !! Besides addition, subtraction, multiplication, and division, Python also supports  exponentiation , which is the raising of one number to the power of another. This operation is performed using two asterisks. >>> 2**5 32 >>> 9 ** (1/2) 3.0      Quotient & Remainder !! To determine the  quotient  and  remainder  of a division, use the  floor division  and  modulo  operators, respectively. Floor division is done using two forward slashes. The modulo operator is carried out with a percent symbol (%). These operators can be used with both floats and integers. This code shows that 6 goes into 20 three times, and the remainder when 1.25 is divided by 0.5 is 0.25. >>> 20 // 6 3 >>> 1.25 % 0.5 0.25 In the example above, 20 % 6 will return 2, because 3*6+2 is equal to 20. You can chain exponentiations together. In other words, you can rise a number to multiple powers...

Floats Floats  are used in Python to represent numbers that aren't integers. Some examples of numbers that are represented as floats are 0.5 and -7.8237591. They can be created directly by entering a number with a decimal point, or by using operations such as division on integers. Extra zeros at the number's end are ignored. >>> 3/4 0.75 >>> 9.8765000 9.8765     Floats As you saw previously, dividing any two integers produces a  float . A  float  is also produced by running an operation on two floats, or on a  float  and an  integer . >>> 8 / 2 4.0 >>> 6 * 7.0 42.0 >>> 4 + 1.65 5.65 A  float  can be added to an  integer , because Python silently converts the  integer  to a  float . However, this implicit conversion is the  exception  rather the rule in Python - usually you have to convert values manually if you want to operate on them. Computers can't sto...

Simple Operations Python has the capability of carrying out calculations. Enter a calculation directly into the Python console, and it will output the answer. >>> 2 + 2 4 >>> 5 + 4 - 3 6 Simple Operations The minus sign indicates a  negative  number. Operations are performed on negative numbers, just as they are on positive ones. >>> -7 -7 >>> (-7 + 2) * (-4) 20 Python also carries out multiplication and division, using an  asterisk  to indicate multiplication and a  forward slash  to indicate division. Use  parentheses  to determine which operations are performed first. >>> 2 * (3 + 4) 14 >>> 10 / 2 5.0 Using a single slash to divide numbers produces a decimal (or  float , as it is called in programming). We'll have more about  floats  in a later lesson. The spaces around the plus and minus signs here are  optional  (the code would work without them), b...

Printing Text !!  The  print  statement can also be used to output multiple lines of text. For Example: >>> print('Hello world!') Hello world! >>> print('Hello world!') Hello world! >>> print('Spam and eggs...') Spam and eggs... Try It Yourself Python code often contains references to the comedy group  Monty Python . This is why the words, "spam" and "eggs" are often used as placeholder variables in Python where "foo" and "bar" would be used in other programming languages.