C Plus Plus Programming: lectures

The computer has to be told how to process data.
This task is accomplished through the use of operators in high level languages
Operators are data connectors within expressions and equations
The type of operator used in problem solving are mathematical, relational, and logical.
The operand and the resultant are two concepts related to the operator
Operands are the data that the operator connects and processes.
The resultant is the answer that results when the operation is completed. For example 5 + 7

Mathematical Operators:
+, -, /, *, \, MOD, ^

Relational Operators:
<, >, ==, !=, <=, >=

Operands of relational operators can either be numeric or character, however, they must be of the same type.
The resultant of relational operation is of logical data type (i.e. either True or False).

Logical Operators:
AND, OR, NOT

Logical operators are used to connect relational expressions and to perform operations on logical data.

Operator Precedence:

The data the computer uses are of many different types.
Computer must be told about the data type of each variable or constant.

Numeric Data

Includes all types of numbers. The subtypes of numeric data type are Integer and Real
Integers are whole numbers
Real numbers or floating point numbers are whole numbers plus decimal parts
A real number can be represented in scientific notation such as 2.5E5 or 3.2E-3. No commas are used.

Character Data

The character data set consists of all single digit numbers, letters and special characters, available to the computer – placed within quotation marks.
An uppercase letter is considered different from a lowercase letter.
When more than one character is put together, the computer considers this item as a string.
Character and string data are compared and arranged in alphabetical order.
The computer gives each character a number (ASCII Codes). The numbers are compared to see which is larger and are then arranged in ascending order.
Upper case letters are given a smaller value than a lowercase letter.

Logical Data

Data:

Constants:

A constant is a specific alphabetical and/or numerical value that never changes during the processing of all the instructions in the solution
Constants can be any type of data – numeric, alphabetical, etc.
In many programming languages and applications constants can be named
In this case, the constant is given a location in memory and a name
Once the constant is given a value, it cannot be changed during the execution of the program, e.g., the value of PI.
The only way to change the value of a constant is to change the program.
Many name conventions stipulate that named constants be given names containing ALL CAPITAL LETTERS in order to easily distinguish them from variables.

Variables:

The value of a variable may change during processing
In many languages variables are called identifiers since the name identifies what the value represents
The programmer uses variable name as a reference name for a specific value of the variable
The computer sets up a specific memory location to hold the value of each variable name found in the program
The variable name should be consistent with what the value of the variable represents.

Rules for naming the variables:

Name the variable according to what it represents
Do not use spaces in the variable names
Start a variable name with a letter
Do not use hyphens or special symbols except underscore
Be consistent when using upper and lowercase letters
Use the exact variable name when referencing that variable in any part of the program
Use the exact variable name when referencing that variable in any part of the program
Use the naming conventions specified by the organization where you work, e.g. all uppercase letters for constants and first uppercase letter for every word used in variable name.

Friday, 25 January 2013