Unit 7 - Programming

• Variables are the values that can be changed in a program. They are used to store data.
• Constants are values that are used in the program and do not change.
• Operators are used to perform calculations and assign values to variables.
• Inputs are data that needs to be input by the user.
• Outputs are the data that is output at the end of the program.
• Assignment is the use of = to assign a value to a variable.
• Sequence is the order that the program has to be in to work correctly.
• Iteration allows a program to repeat a set of instructions a specified number of times.
• Selection is a decision or a question.
• Boolean operators decide whether a statement is true or false.
• MOD is the remainder of a division equation.
• SQL stands for Structured Query Language
• SELECT lists the fields to be displayed (comes 1st)
• SQL statements can be used in Python to create a database, add, amend, delete records and fields and search for data.
• FROM specifies the table name (comes 2nd)
• WHERE lists the search criteria (comes 3rd)
• ORDER BY can be used to order the data in a specific way (comes 4th)
• Subroutines are small programs that are called by the main program to perform a specific task.
• Functions and procedures are both subroutines.
• Functions will return a value after processing takes place while procedures will not.
• Parameters are the names listed in the function definition.
• Arguments are the real values passed into a function.
• Subroutines are used useful to break up large programs into smaller units.
• Subroutines can be stored in a subroutine library to be used later.
• Subroutines make program maintenance easier.
• Local variables are variables declared inside a function and can only be used inside the function.
• Global variables are variables declared outside a function and can be used anywhere in the program.
• Arrays are data structures that allow you to hold many items of data which is referenced by one identifier.
• All items of data in the array must be the same data type.
• An array of 10 strings called userNames could be declared as: array userNames[10]
• Information can be read from or written to the array using the index number.
• In Python, the index number starts at 0.
• An array has a fixed length.
• Python does not have arrays. Instead, lists are used.
• A list has a changeable length.
• A for loop that could be used to output the data in an array of usernames is: for i = usernames.length: print(usernames[i])