2621008 - C++ 2

Expressions
In C++, there are many special characters with particular
meanings. Examples include the arithmetic operators:
Relational, Equality, and Logical Operators
Just as with other operators, the relational, equality, and logical operators
have rules of precedence and associativity that determine precisely how
expressions involving them are evaluated. C++ systems use the bool values
true and false to direct the flow of control in the various statement types.

Expressions
Relational, Equality, and Logical Operators
the relational, equality, and logical operators have rules of precedence and
associativity that determine precisely how expressions involving them are
evaluated. C++ systems use the bool values true and false to direct the flow
of control in the various statement types.

Expressions
Logical AND (&&)
p q p && q
T T
T F
F T
F F

Expressions
Logical AND (&&)
p q p && q
T T T
T F F
F T F
F F F

Expressions
Logical OR
p q p || q
T T
T F
F T
F F

Expressions
Logical OR
p q p || q
T T T
T F T
F T T
F F F

Expressions
Logical negation
p !p
T
F

Expressions
Logical negation
p !p
T F
F T

Bitwise Operators
Slide 10
Bitwise operation means convert the number into binary and the carry out the
operation on each bit individually. For example let us take the operation
complement represented by symbol (~). Let me take a number
short A = 42;
A short number is stored in two byte or 16 bits. Therefore,
A when expressed in binary = 00000000 00101010
Complement of A is ~A = 11111111 11010101
Contd...

#include<iostream>
using namespace std;
void main()
{ short A =42;
short B = 12;
int C = A|B;
int D = A<<1;
cout << "C = "<<C <<endl;
cout<< "D = "<<D <<endl;
}
Bitwise Operators
The expected output is as under.
C = 46
D = 84

#include<iostream>
void main()
{short A =42;
short B = 12;
short C = 24;
short D = A^B; // XOR operator
C <<= 1;
A <<=2; // Shift to left by 2 places and assign
B >>=2 ; // shift right by 2 places and assign
cout<< "A = "<<A<< " tB = "<< B <<endl;
cout << "C = "<<C <<endl;
cout << "D = "<< D <<endl;
}
The expected output is given below.
A = 168 B = 3
C = 48
D = 38

Operators common to C++
Slide 14

Operator Precedence
In C++, you use operators and expressions such as the following:
int MyNumber = 10 * 30 + 20 – 5 * 5 << 2;
The question is, what value would MyNumber contain? The order in which the
various operators are invoked is very strictly specified by the C++ standard.
This order is what is meant by operator precedence.

Assignment and Expressions
C++ provides assignment operators that combine an assignment operator
and some other operator.
C++ also provides increment (++) and decrement (--) operators in both
prefix and postfix form.

Assignment and Expressions
The postfix form behaves differently from the prefix form:

PROGRAMMING WITH VISUAL C++
C++ Relational, Equality, and Logical

Statements
C++ has a large variety of statement types, including an
expression statement. For example, the assignment
statement in C++ is syntactically an assignment expression
followed by a semicolon.
There are two
statements:
The Simple
Statement
The Compound
Statement

The Compound Statement
The Compound Statement
• A compound statement in C++ is a series of statements
surrounded by braces { and }.
• The body of a C++ function, for example, is always a compound
statement.

Conditional ternary operator ( ? )
Slide 24
The conditional operator evaluates an expression, returning first value if that
expression evaluates to true, and a different one if the expression evaluates as
false. Its syntax is:
condition ? result1 : result2
7==5 ? 4 : 3 // evaluates to 3, since 7 is not equal to 5.
7==5+2 ? 4 : 3 // evaluates to 4, since 7 is equal to 5+2.
5>3 ? a : b // evaluates to the value of a, since 5 is greater than 3.
a>b ? a : b // evaluates to whichever is greater, a or b.

For example:
// conditional operator
#include <iostream>
int main ()
{
int a,b,c;
a=2;
b=7;
c = (a>b) ? a : b;
cout << c << 'n';
}
In this example, a was 2, and b was 7, so the expression being evaluated (a>b)
was not true, thus the first value specified after the question mark was discarded
in favor of the second value (the one after the colon) which was b (with a value
of 7).

The if and if-else Statements
if and if-else
The general form of an if statement is:
Here is an example of an if statement:
Or another example:

Closely related to the if statement is the if-else statement,
which has the general form
if and if-else

If condition is true, then statement1 is executed and
statement2 is skipped; if condition is false, then
statement1 is skipped and statement2 is executed.
After the if-else statement has been executed, control
passes to the next statement. Consider the next code:
if and if-else

If x < y is true, then min is assigned the value of x;
if x < y is false, min is assigned the value of y. After
the if-else statement is executed, min is printed.
if and if-else

The switch Statement
The switch statement is a multiway conditional
statement generalizing the if-else statement. The
general form of the switch statement is given by

switch (expression)
{
case constant1:
group-of-statements-1;
break;
case constant2:
group-of-statements-2;
break;
.
.
.
default:
default-group-of-statements
}

Ex:

2621008 - C++ 2

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