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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 truetrue and falsefalse to direct the flow of control in the various statement types.

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ExpressionsRelational, 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 truetrue and falsefalse to direct the flow of control in the various statement types.

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ExpressionsLogical AND (&&)

p q p && q

T T

T F

F T

F F

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ExpressionsLogical AND (&&)

p q p && q

T T T

T F F

F T F

F F F

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ExpressionsLogical OR

p q p || q

T T

T F

F T

F F

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ExpressionsLogical OR

p q p || q

T T T

T F T

F T T

F F F

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ExpressionsLogical negation

p !p

T

F

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ExpressionsLogical negation

p !p

T F

F T

Bitwise Operators

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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 numbershort A = 42;A short number is stored in two byte or 16 bits. Therefore,

A when expressed in binary = 00000000 00101010Complement of A is ~A = 11111111 11010101

Contd...

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Bitwise Operators

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#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 = 46D = 84

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#include<iostream>using namespace std;void main(){short A =42;short B = 12;short C = 24;short D = A^B; // XOR operatorC <<= 1;A <<=2; // Shift to left by 2 places and assignB >>=2 ; // shift right by 2 places and assigncout<< "A = "<<A<< " \tB = "<< B <<endl;cout << "C = "<<C <<endl;cout << "D = "<< D <<endl;}

The expected output is given below.A = 168 B = 3C = 48D = 38

Operators common to C++

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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.

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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.

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Assignment and Expressions

The postfix form behaves differently from the prefix form:

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PROGRAMMING WITH VISUAL C++

C++ Relational, Equality, and Logical

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PROGRAMMING WITH VISUAL C++

C++ Relational, Equality, and Logical

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PROGRAMMING WITH VISUAL C++

C++ Relational, Equality, and Logical

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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.

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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 ( ? )

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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.

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For example:// conditional operator#include <iostream>using namespace std;

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).

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The if if and if-elseif-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:

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

if and if-else

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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

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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

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

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

default: default-group-of-statements}

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The switch Statement

Ex: