C++ Notes

Thought i would keep this updated time to time, as i found a good Ebook to teach me step by step C++ as well as making files, running them, creating expressions, keywords and alot of other things, this is what i have for you so far:

Constans are the fixed values that do not change during the programs execution.

-Rules for Constructing Variable Names-

-A variable name is any combination of 1 to 8 alphabets,digits,or underscores, some compilers allow variable name whos length can be uo to 40

characters.

-the first character in the variable name, must be an alphabet

-No commas or spaces are allowed withing the variable name

-No special symbols other than an underscore can be used in a variable name.

-Uppercase and lowercase are significant. That is the variavle tota is not the same as total or TOTAL.

-The variable should not be a keyword

-white space is not allowed..

The Assignment operator is used for assigning a value to a variable, the syntax for this is like this.

General Format-
Variable =expression;

-Example-
year = 2004;
age = year - dob;
i = i + 1;

The logical operators are used to combine two expressions

C++ includes two useful operators not generally found in other programming languages these are the Increment(++) and Decrement operators(-

-).
The operator ++ adds 1 to itts operand and -- subtracts one. In other words x = x+1 is the same as ++x and x= x-1 is the same as --x


Prefix- First incriments/decremnts and then assigns the value
Postfix- First assigns the value and then Increments/Decrements

The increment and Decrement operators can either be used as a prefix or a postfix to the variable. ++ variable and variable ++ have DIFFERENT.

meening.

The prefix operator ++ variable or -- variable first increments or decrements the value as they case may be, and then assings the value to the

variable. On the contratry, The postfix operator Variable ++ or variable -- first assings the value, and then increments and decrements the value

of the variable.

Prefix ++variable --variable
Postfix variable++ variable--

The conditional operators(also known as ternary operators) and '?' and ':', these are used to construct conditional expressions.

EX.

exp = exp 1 ? exp 2:exp 3:

? : - Conditional Operator

------------------
Example--

if exp1 is true

then exp=exp2:

else exp=exp3:

Expression one is evaluated first, if it is true than expression 2 is evaluated and becomes the value of the expression, but in case if expression 1 is false, than expression 3 is evaluated and its value becomes the expression.

Examples of Conditonal Operator--

m = 15:

n = 8:

z = (m>n) ? M : n:

In that example, the variable m is assigned a value of 15 and n is assigned the value of 8. Here, in the state ment shown in the figure, first the condition m>n is checked, IF the condition returns false the value of n is assigned to the variable z. hence z would contain the value of n.

a = -10:

n = -last;


Unary Minus Operator- negates the value of a number or variable. It is equivalent to multiplying the value of the number or variable by -1 the figure shows some examples of unary minus operator.