C++ course (third section 1)

C++ course (third section 1)

C++ course

third section(write your first C++ program 1)

First you must know some main important things about the program:

Assignment Statement

•The assignment statement takes the form:

variable=expression 

•Expression is evaluated and its value is assigned to the variable on the left side 
•In C++, = is called the assignment operator

i.e int num1,num2;

double sale;

char first;

string str;

num1=4;

num2=4*3-7;

sale=0.02;

first='A';

str="have a nice day";

OR

int num1=3;

int num2=6;

double sale=2.5;

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Input (Read) Statement

•cin is used with >> to gather input

cin>>variable>>variable;

•The stream extraction operator is >> 
•For example, if miles is a double variable 
cin >> miles;
−Causes computer to get a value of type double Places it in the variable miles

•Using more than one variable in cin allows more than one value to be read at a time
•For example, if feet and inches are variables of type int, a statement such as:
cin >> feet >> inches;
−Inputs two integers from the keyboard
−Places them in variables feet and inches respectively

Increment & Decrement Operators

•Increment operator: increment variable by 1
−Pre-increment: ++variable
−Post-increment: variable++
•Decrement operator: decrement variable by 1
−Pre-decrement: --variable
−Post-decrement: variable—
•What is the difference between the following?

1)
x = 5; 
y = ++x;


2)
x = 5; 
y = x++;

The first one you increment x by 1 (which become 6) then keep it and print it if you want,

The second one you keep the value of x which is 5 and print it if you want then you increment it by one.

Output(write) statement

•The syntax of cout and << is:

cout<<expression or manipulator<<expression;

−Called an output statement 
•The stream insertion operator is << 
•Expression evaluated and its value is printed at the current cursor position on the screen

•A manipulator is used to format the output
−Example: endl causes insertion point to move to beginning of next line

i.e cout<<x<<endl;

•The new line character is '\n' 
−May appear anywhere in the string 
cout << "Hello there.";
cout << "My name is James.";
•Output: 
Hello there.My name is James.

cout << "Hello there.\n";
cout << "My name is James.";
•Output : 
Hello there.
My name is James.

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