// This program calculates the area of a rectangle.
// By Frank McCown
#include <iostream>
using namespace std;
int main() {
int width;
int height;
int area;
cout << "Width? ";
cin >> width;
cout << "Height? ";
cin >> height;
area = width * height;
cout << "Area is " << area;
return 0;
}
// or surrounded by /* */
// This is a single line comment. /* This is a multi-line comment. */
// is ignored by the compiler
int x; // This comment is ignored by the compiler
#include <library-name>
iostream is a library that sends output to
the console (cout) and reads input from the keyboard via
the console (cin)
using statement is necessary, but don't worry about
what it's used for now
int main() is the beginning of the executable statements
{ and } to surround statements
return 0; at the end says the program finished successfully
int means that the variable may hold integers (no decimal place),
like 2 and -10
width, height, area are the three variables used in the program
w,
h and a,
but using complete words makes our programs easier to understand and is
preferred by most programmers
using or int
int test5_0; // OK int test50%; // WRONG (% is not a legal char) int test 50; // WRONG (space is not legal)
int test_2; // OK int _2test; // OK int 2_test; // WRONG (starts with digit)
width and Width
are not the same variable!
<< to send
string literals like
"Hello!" and the value of variables to the console
cout << "height is " << height;
/* Outputs: Hello there! */ cout << "Hello" << endl << "there!";
>> with a variable to read a
number from the keyboard into the variable
// Read a number into x cin >> x; // Read in three numbers cin >> x >> y >> z;
=
final = 80.0;
=
80.0 = final; // Syntax error!
// Calculate the average of the final and midterm aveGrade = (final + midterm) / 2; // Wrong since since / is done first! aveGrade = final + midterm / 2;