C++ Part 18

A SINGLE STATEMENT FOR EACH ALTERNATIVE

if (Boolean_Expression) Yes_Statement else No_Statement If the Boolean_Expression evaluates to true, then the Yes_Statement is executed. If the Boolean_Expression evaluates to false, then the No_Statement is executed.

Multi if-else Statement

if (Boolean_Expression_1) Statement_1 else if (Boolean_Expression_2) Statement_2 . . . else if (Boolean_Expression_n) Statement_n else Statement_For_All_Other_Possibilities // EXAMPLE if ((temperature < -10) && (day == SUNDAY)) cout << "Stay home."; else if (temperature < -10) // and day != SUNDAY cout << "Stay home, but call work."; else if (temperature <= 0) // and temperature >= -10 cout << "Dress warm."; else // temperature > 0 cout << "Work hard and play hard.";

C++ Part 13

Types of Control

• Selection: Execute a different instruction depending on the result of evaluating some [Boolean] condition.
• if/else, multiway if, switch, ? :
• Iteration: Repetitively execute some instruction until some condition is met.
•  for, while, do while.

Conditions

A condition is a Boolean expression - i.e., one that evaluates to true or false.
Most commonly either a relational operator or a logical combination of conditions:
Relational (Comparison) Operators:== != < > <= >=
Logical operators:! && ||

For example :  

• n <= 100 && n >= 0  // n less than equal to AND n must be greater than 0
• n< 101 && n >= 0  // n less than 101 AND n greater than equal to 0
• grade> ’c’ && grade <= ’f’ // grade greater than 'c' ( character c ) AND less than equal to 'f'
• y< x && y >= 0   // 

Intro to C++ Part 6

A Sample C++ Program  

##include <iostream>
using namespace std;The following line says that main is a function with no parameters that returns an int(integer) value:int main( )Some compilers will allow you to omit the int or replace it with void, which indicates
a function that does not return a value. However, the previous form is the most
universally accepted way to start the main function of a C++ program.
The program ends when the following statement is executed:return 0;