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The flow of control refers to the order in which a program’s statements are executed. Unless directed otherwise, the normal flow of control for all programs is sequential. This means that statements are executed in sequence, one after another, in the order in which they are placed within the program. Selection, repetition and function invocation structures permit the flow of control to be altered in defined ways. This chapter introduces to you C++’s selection statements. Repetition and invocation techniques are presented in the next two chapters.

Selection criteria

Relational operators

Relational operators are used to compare two operands for equality and to determine if one numeric value is greater than another. A Boolean value of true or false is returned after two operands are compared. The list of relational operators is given below.

Relational operators


a = = b

(a*b) != c

s == ‘y’

x<= 4

The value of a relational expression such as a>40 depends on the value stored in the variable a.

Logical operators

Logical operators, AND, OR and NOT are used for creating more complex conditions. Like relational operators, a Boolean value of true or false is returned after the logical operation is executed.

When the AND operator,&&, is used with two simple expressions, the condition is true only if both individual expressions are true by themselves.

The logical OR operator, ||, is also applied with two expressions. When using the OR operator, the condition is satisfied if either one or both of the two expressions are true.

The NOT operator,!, is used to change an expression to its opposite state; thus, if the expression has any nonzero value (true),! expression produces a zero value (false). If an expression is false,! expression is true (and evaluates to false).



(age>40) || (term<10)


( i==j) || (a<b) || complete

The relational and logical operators have a hierarchy of execution similar to the arithmetic operators. The following table lists the precedence of these operators in relation to the other operators we have used.

Associativity of operators

Example: Assume the following declarations:

char key = ‘m’;

int i = 5, j = 7, k = 12;

double x = 22.5;

Results of expressions
By evaluating the expressions within parentheses first, the following compound condition is evaluated as:

Evaluation process

The bool data type

As specified by the ANSO/ISO standard, C++ has a built-in Boolean data type, bool, containing the two values true and false. As currently implemented, the actual values represented by the bool values, true and false, are the integer values 1 and 0, respectively. For example, consider the following program, which declares two Boolean variables:



int main()


bool t1, t2;

t1 = true;

t2 = false;

cout<<“The value of t1 is “<<t1

<<“\n and the value of t2 is “<<t2<<endl;

return 0;


The output of the program is:

The value of t1 is 1

and the value of t2 is 0

The if-else statement

The if-else statement directs the computer to select a sequence of one or more statements based on the result of a comparison.

Questions & Answers

explain and give four Example hyperbolic function
Lukman Reply
The denominator of a certain fraction is 9 more than the numerator. If 6 is added to both terms of the fraction, the value of the fraction becomes 2/3. Find the original fraction. 2. The sum of the least and greatest of 3 consecutive integers is 60. What are the valu
1. x + 6 2 -------------- = _ x + 9 + 6 3 x + 6 3 ----------- x -- (cross multiply) x + 15 2 3(x + 6) = 2(x + 15) 3x + 18 = 2x + 30 (-2x from both) x + 18 = 30 (-18 from both) x = 12 Test: 12 + 6 18 2 -------------- = --- = --- 12 + 9 + 6 27 3
2. (x) + (x + 2) = 60 2x + 2 = 60 2x = 58 x = 29 29, 30, & 31
Mark and Don are planning to sell each of their marble collections at a garage sale. If Don has 1 more than 3 times the number of marbles Mark has, how many does each boy have to sell if the total number of marbles is 113?
mariel Reply
Mark = x,. Don = 3x + 1 x + 3x + 1 = 113 4x = 112, x = 28 Mark = 28, Don = 85, 28 + 85 = 113
how do I set up the problem?
Harshika Reply
what is a solution set?
find the subring of gaussian integers?
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Shirley Reply
please can go further on polynomials quadratic
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I need quadratic equation link to Alpa Beta
Abdullahi Reply
find the value of 2x=32
Felix Reply
divide by 2 on each side of the equal sign to solve for x
Want to review on complex number 1.What are complex number 2.How to solve complex number problems.
yes i wantt to review
use the y -intercept and slope to sketch the graph of the equation y=6x
Only Reply
how do we prove the quadratic formular
Seidu Reply
please help me prove quadratic formula
hello, if you have a question about Algebra 2. I may be able to help. I am an Algebra 2 Teacher
Shirley Reply
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what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
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Solve for the first variable in one of the equations, then substitute the result into the other equation. Point For: (6111,4111,−411)(6111,4111,-411) Equation Form: x=6111,y=4111,z=−411x=6111,y=4111,z=-411
x=61/11 y=41/11 z=−4/11 x=61/11 y=41/11 z=-4/11
Need help solving this problem (2/7)^-2
Simone Reply
what is the coefficient of -4×
Mehri Reply
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
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Source:  OpenStax, Programming fundamentals in c++. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10788/1.1
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