2.2 Programming

2.2 Programming

1. Variables

   • Adds a memory label to a literal value for example Name = Bob.

2. Operators

   • Boolean data type is a data type that has one of two possible values (usually denoted true and false), intended to represent the two truth values of logic and Boolean algebra.
   • Arithmetic
     • An arithmetic operator is a mathematical function that takes two operands and performs a calculation on them. They are used in common arithmetic and most computer languages contain a set of such operators that can be used within equations to perform a number of types of sequential calculation.
   • String
     • string is traditionally a sequence of characters, either as a literal constant or as some kind of variable. The latter may allow its elements to be mutated and the length changed, or it may be fixed (after creation).
   • concatenate
     • is the operation of joining two strings together. The term"concatenation" literally means to merge two things together. Also known as string concatenation.
   • Substring
     • A subset of an alphanumeric field or variable. The substring function in a programming language is used to extract the subset; for example, the programming expression substr(prodcode,4,3) extracts characters 4, 5 and 6 out of a product code field or variable.
   • Boolean
     • Boolean data type is a data type that has one of two possible values (usually denoted true and false), intended to represent the two truth values of logic and Boolean algebra.
   • Delimiter
     • A delimiter is a sequence of one or more characters used to specify the boundary between separate, independent regions in plain text or other data streams.
   • Modulus
     • In computing, the modulo operation finds the remainder after division of one number by another (sometimes called modulus). Given two positive numbers, a (the dividend) and n (the divisor), a modulo n (abbreviated as a mod n) is the remainder of the Euclidean division of a by n.

3. Sequence

   • Efficiency
     • In computer science terms efficiency is the ratio of useful work to resources (processor and storage) expended. In other words, the ratio of the output to the input of a given system.
     • Structured programming is a programming paradigm aimed at improving the clarity, quality, and development time of a computer program by making extensive use of the structured control flow constructs of selection (if/then/else) and repetition (while and for), block structures, and subroutines.

4. Selection

   • Select case
     • A selection is used to make choices based on information. An algorithm can be made more intelligent by using IF, THEN and ELSE to repeat instructions or move to different parts of the program. An explanation of selection, as used in algorithms and programming.
   • Nested
     • Nesting is quite common in programming, where different logic structures sequence, selection and loop) are combined (i.e., nested in one another). It also occurs in applications. For example, many word processing applications allow you to embed (nest) one document inside another.

5. Iteration

   • Iteration
     • Iteration, in the context of computer programming, is a process wherein a set of instructions or structures are repeated in a sequence a specified number of times or until a condition is met. When the first set of instructions is executed again, it is called an iteration.

6. ASCII AND UNICODE

   • ASCII is the 7 bit value associated with each letter or number oon the keyboard
     • Maximum of 127 numbers
   • UNICODE is used for further characters for example emojis. Can be 8,16,32 bit

7. SQL

   • SQL stands for Standard Query Language, a popular human-readable programming language that is used to work with databases
   • These databases are not stored in text files or CSV files but in binary proprietary formats, of which the more common ones include MySQL, SQLlite, MsAccess, Oracle, etc.
   • SELECT*FROM Results WHERE Result > 80
     • FROM tells it where to pull this data from
     • WHERE is the criteria in this case the result being > 80
     • SELECT tells it what to do in this case select all, symbolised by *

8. Record

   • Records stored in text files
     • -Stored on the hard disk
       • -Used to store data while the program is not running
         • -Useful for small volumes of data
           • -Each field is stored on a new line or separated with an identifier such as a comma (CSV file) or tab
   • Records stored in arrays
     • -Stored in ram
       • -Used to store data while the program is running
         • -Useful for volumes of data
           • -Can be single or multi-dimensional allowing for tables of data to be stored
             • -Uses indexes to refer to data items
               • -Efficient algorithms or linear searches can be used to find data

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