C++ Conditional statements and Operators

Operators are used to make expressions and conditional statements works with expressions so we need to know about operators.

We have five kinds of operators in C++:

§  Assignment operator : 

               ( = ) used to assign right-side value to left-side value

§  Arithmetic operators :

§  ( + )        2+2=4

§  ( - )         2-2=0

§  ( * )        2*2=4

§  ( / )         2/2=1

§  ( % )       2%2=0

§   Increment/Decrement:

§   ( ++ )     VarName++

§    ( -- )     VarName--

§  Relational operators :

§  ( < )        2<2=0

§  ( > )        2>2=0

§  ( <= )      2<=2=1

§  ( >= )      2>=2=1

§  ( == )      2==2=1

§  Logical operators:

§  ( && )    1&&1 = 1              and

§  ( || )      0||0 =0                      or

§  ( ! )         !0 = 1                     not

§  :Increment and decrement:
            §  ( ++ )       1++ = 2
            §  ( -- )         2--  = 1
§  Compound assignment operators:

§  ( += )      x += y    (x = x + y)

§  ( -= )       x -= y     (x = x – y)

§  ( *= )      x *= y    (x = x * y)

§  ( /= )      x /= y     (x = x / y)

§  ( %= )     x %=y    (x = x % y)

Conditional statements

Conditional statements have very simple rules if their condition was true the statements will be executed otherwise compiler will skip that statement and execute the default statement.

We have two kinds of conditional statement in C++:

if statement:

structure of if statement:

                if ( condition ) { codes; }            else if ( condition ) { codes; }      …         else { codes; }

if key word:

in order to use if key word we have to write if keyword at the beginning of the statement so compiler will threat it like if statement. We can use if statement alone without any else if or else statement after it.

Condition:

A condition is made of operators will be used in here inside prentices ( ( ) ) their result may be one of these two values true or false. Conditions are two type simple conditions ( conditions that don’t have any logical operator in them ) and compound conditions ( conditions that  have logical operator in them , these logical operators connect two simple conditions ) which both can be used in if condition. We can use true or false directly like a condition.

Codes:

In here codes can be our commands that will be executed after the condition was true. Each curly braces in C++ makes a scope so variables inside inner curly braces can’t be called from the outer scopes.

else if:

else if can only be used after if statement and it depends on if statement, I mean if statement always will be checked first if the condition was false it will come to check else if statements and if all else if statements was false it will execute the else but if the if statement was true compiler will not execute else if condition even if they are true because else if condition are depending into if condition.

else:

else statements are used as default , they will be executed if  the if condition and all else if conditions was false. Of course, if there was not any else if statement it will not complain.

Nested if :

We can write if condition (with or without else if and else) inside another if, else if and else statements to create nested if:

       

         If ( condition ) { if ( condition ) { codes; } }

switch statement:

structure of switch statement in C++:

     switch( value )

    {

          case value1 : { codes; break; }

          case value2 :

          case value3 : { codes; break; }

          .

          .

          .

          default : { codes; } 

    }

switch keyword:

in order to use switch statement, we have to write switch keyword at the start of the statement.

Value:

switch statements are using value inside prentices ( ( ) ) to check them if it has any case with that value if that was true the case with same value will be executed otherwise the default will be executed.

Case and break:

Cases have values with them switch statement will compare that value with the value of itself if that matches the case codes will be executed but the problem is this which it will continue executing next cases in order to avoid it we need to put a break key word before ending of each case.

We can put more than one case back to back to make the same code for those values like example above.

Default:

If all cases values were deferent from switch value the default will be executed.

Ternary operator:

Syntax for the ternary operator in C++.

( condition )? codes : codes ;

                

                Condition:  It is explained in if condition.

                

                ( ? ) :           codes after  this symbol will be executed if the condition was true

                

                ( : ) :            codes after this symbol will be executed if the condition was false

                

            We can write values instead of codes, it will return value if the condition was true or false:

            

                    DataType VarName = ( condition ) ? value : value ;

     

Note: 

other commands like cout can be used instead of value in ternary operators but in that case we cannot assign that to a value because it will not return any value.