BASIC ELEMENTS OF C++
BASIC ELEMENTS OF
C++
OBJECTIVES
To be able to use C++ input/output and formatting
To become familiar with the C++ standard
Outcome
Know how to write your first program in C++ using basic elements of C++.
Hello C++!
// This is a C++ program. It prints the sentence:// Welcome to C++ Programming.
#include <iostream>using namespace std;
int main(){ cout << "Welcome to C++ Programming!"
<<endl; system("Pause"); return 0;}
Your First Program – Explained
Your First Program – Explained
#include<iostream> - read the file iostream that contains the definition for the stream input/output package.
using namespace std; - all names in the program belong to the "standard namespace"
cout << "Hello World!" << endl;
• Each C++ statement ends in a semicolon.• "Hello World!" is called a string.• The endl symbol denotes an end of line marker.• OR:
cout << "Hello World!\n";
• The sequence of characters enclosed in quotations marks ("Hello, World\n") is called a string. – Escape sequence indicates a newline.
Your First Program – Explained – The Output Statement
New Line \n or endl
#include <iostream>using namespace std;
int main(){ cout<< "Hello there."; cout<< "My name is Siti."<<endl<<endl; cout<< "Hello there.\n"; cout<< "My name is Siti.\n\n"; cout<< "Hello \nthere. \nMy name is Siti. \
n"; system("Pause"); return 0;}
Comments
Comments can be written in two styles:Single line:
double can_volume = 0.355; // Liters in a 12-ounce can
Multiline for longer comments:
/* This program computes the volume (in liters) of a six-pack of soda cans.
*/
Basic data types in C++Data type C++ keyword Range
Integer int -32768 to 32767
Long integer long -4294967296 to 4294967295
Short integer short -128 to 127
Unsigned integer unsigned 0 to 65535
Character char 0 to 255
Floating point float 6 digits of precision
Double floating point double 12 digits of precision
float amount; //Declares amount as a floating-point variable
int number; //Declares number as an integer variable
char ch; //Declares ch as a character variable
C++ operators
Several classes of operators Arithmetic Relational Logical Assignment
Arithmetic operators
Seven arithmetic operators in C++ ( E.g. int a = 7, b = 2; )
Operators Action
- Substraction
+ Addition
* Multiplication
/ Division
% Modulus division
- - Decrement
+ + Increment
Expression Value
a - b 5
a + b 9
a * b 14
a / b 3
a % b 1
a-- 6
b++ 3
Arithmetic Operators (Integer)
#include <iostream>using namespace std;
int main(){ // Integers Expression cout << "2 + 5 = "<< 2 + 5 << endl;
cout << "4 * 3= "<< 4 * 3 << endl; cout << "5 / 2= "<< 5 / 2 << endl; return 0;}
Arithmetic Operators (Float)
#include <iostream>using namespace std;
int main(){ // Floating-point expression
cout<<"34.0 - 20.0 = "<<34.0 - 20.0<<endl; cout<<"4.0 * 3.0= "<<4.0 * 3.0<<endl; cout<<"5.0 / 2.0= "<<5.0 / 2.0<<endl; return 0;}
Arithmetic Operators (Mix)
#include <iostream>using namespace std;
int main(){ // Mix expression cout<<"3 / 2 + 5.5 = "<<3 / 2 +
5.5<<endl; return 0;}
Relational operators
Six relational operators in C++The results is either TRUE (1) or FALSE (0)E.g. if a = 7 and b = 5, then a < b yields 0 and a != b
yields 1Operator Meaning
< Less than
<= Less than or equal
> Greater than
>= Greater than or equal
= = Equal
!= Not equal
Logical Operators
&& (logical AND) Returns true if both conditions are true
|| (logical OR) Returns true if either of its conditions are true
! (logical NOT, logical negation) Reverses the truth/falsity of its condition Returns true when its condition is false
Logical operators used as conditions in loops Expression Resulttrue && false falsetrue || false true!false true
Assignment Operators
Most commonly used assignment operator is = (e.g. int Q = 5; )
Assignment expression abbreviationsc = c + 3; can be abbreviated as c += 3; using the
addition assignment operator
Examples of other assignment operators include:d -= 4 (d = d - 4)e *= 5 (e = e * 5)f /= 3 (f = f / 3)g %= 9 (g = g % 9)
Increment and Decrement Operators
Find the value of i and j (Assume i = 1)
int j = ++i // j is 2 , i is 2
int j = i++ // j is 1, I is 2
int j = --i // j is 0, I is 0
int j = i-- //j is 1, I is 0
Type Conversion (Casting)#include <iostream>using namespace std;int main(){ cout<<"7.9 (int) =
"<<static_cast<int>(7.9)<<endl; cout<<"25 (double) =
"<<static_cast<double>(25)<<endl; cout<<"5 + 3 (double) = " <<static_cast<double>(5 + 3)<<endl; cout<<"(15) / 2 (double) = " <<static_cast<double>(15) /
2<<endl<<endl; return 0;}
Allocating Memory with Constants
const double CONVERSION = 2.54;const int NO_OF_STUDENTS = 20;const char BLANK = ‘ ‘;const double PAY_RATE = 15.75;
Constant? A memory location whose content is not allowed to change during program execution.
Allocating Memory with Variables
double sale;int num1, num2;char first;string str;Variable? A memory location whose content
may change during program execution.num1 = 4; num2 = 4*5-11;sale = 0.02 * 1000;first = ‘D’; str = “It is a sunny
day.”;
#include <iostream>using namespace std;
int main(){
const int NO_STUD = 20;
string str; str = “All are good students”;
cout<<“Num of students is “<<NO_STUD;
cout<<str; str = “Some are so-so”; cout<<str;
return 0; }
Input (Read) Statement#include <iostream>using namespace std;int main(){ int feet, inches;
cout<<“Enter two integers separated by spaces: “;
cin>> feet >> inches; cout<<endl;
cout<< “Feet = “<< feet << endl; cout<< “Inches = “<< inches << endl; system(“pause"); return 0;}
Increment & Decrement Operators#include <iostream>using namespace std;int main(){ int num = 0, num2 = 0, tot = 5;
num++; num2 = num2 + 1; cout<< num <<“ “<< ++num <<endl;
tot--; cout<< tot; system("Pause"); return 0;}
Preprocessor Directives
#include <iostream>#include <string>using namespace std;int main(){ int num; string name; cout<<“Enter an integer: “; cin>>num;
cout<<“Enter name: “; cin>>name; return 0; }
Let’s Try!
Write a program that prompts the user to enter two test scores and then prints the average test score. (Assume test scores are decimal numbers.)
Let’s Try!
Write a program that converts Fahrenheit degrees to Celsius using the formula :
Celcius = 5/9 * (Fahrenheit – 32)