Additional Programming Techniques

• String manipulation


  The use of programming techniques to modify, analyse or extract information from a string
• Case conversion


  The ability to change a string from one case to another, e.g. lowercase to uppercase
• Length (string manipulation)


  Finding the length refers to the ability to count the number of characters in a string
• Substring


  The ability to extract a sequence of characters from a larger string using slicing
• Concatenation


  The ability to join two or more strings together to form a single string using the + operator
• ASCII conversion


  The ability to return an ASCII character from a numerical value and vice versa
• In Python substrings are indexed from 0
• Python code


  • print(name.upper())
  • print(len(password))
  • print(FName + SName)
• File handling


  The use of programming techniques to work with information stored in text files
• Python code


  • file = open("fruit.txt", "r")
  • file.close()
  • file.readline()
  • file.write("Oranges")
• "r" mode


  Used for opening a file in read-only mode
• "w" mode


  Used for opening a file in write mode, creating a new file if it doesn't exist, or overwriting an existing file
• "a" mode


  Used for opening a file in append mode, writing to the end of an existing file
• It's important to make a backup of text files before working with them
• Database


  An organised collection of data that allows easy storage, retrieval, and management of information
• Field


  One piece of information relating to one person, item or object, represented as a column in a database
• Record


  A collection of fields relating to one person, item or object, represented as a row in a database
• Array (storing data)


  Useful when working with small amounts of data, stored in main memory (RAM)
• Advantages of using a database


  • Efficient sorting and searching of large amounts of data
  • Multiple user access
  • Better security than text files
• Disadvantages of using text files for data storage


  • It can be difficult to know where one record begins and ends
• Advantages of using arrays for data storage


  • More efficient and faster to search than text files
• When are text files useful for data storage


  Storing small amounts of data on secondary storage when the application is closed
• SQL


  A programming language used to interact with a Database Management System (DBMS)
• SELECT (SQL)


  The SELECT command in SQL is used to retrieve data (fields) from a database table
• FROM (SQL)


  The FROM command in SQL specifies the table(s) to retrieve data from
• WHERE (SQL)


  The WHERE command in SQL filters the data based on a specified condition
• The '*' symbol is a wildcard in SQL
• SQL commands


  • SELECT * FROM Customers;
  • SELECT name, age FROM Customers WHERE age > 30;
  • SELECT country, population FROM world WHERE population < 100000;
• 1D array


  An ordered, static set of elements that can only store one data type
• 2D array


  An ordered, static set of elements that can only store one data type but adds another dimension. It can be visualised as a table with rows and columns
• Python code


  • temp = [1, 2, 3, 4, 5]
  • print(countries[1])
  • students[2] = "Rebecca"
  • scores = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
• 2D arrays can only store one data type in the same array
• Zero-indexing


  Indexes of an array start from 0, not 1
• Function


  A type of sub-program that performs a specific task and returns a value
• Procedure


  A type of sub-program that performs a specific task but does not return a value
• Parameter


  A value that is passed into a sub-program (function or procedure)
• To use a function/procedure it must be 'called'
• Global variable


  A variable declared at the outermost level of a program and can be accessed from any part of the program
• Local variable


  A variable declared within a specific scope, such as a function or code block, and can only be accessed within that scope
• Key difference between function and procedure


  • A function returns a value, whereas a procedure does not return a value