- Basics
- Data Structures
- Loops and Collections
- Functions
- Exception Handling
- Classes
- The IO Library: fstream
- The IO Library: istringstream
- Sequential Containers
- String Operations
- Generic Algorithms
Compiling and Executing a program
Once we created a program we need to compile it. How your compile a program depends on your operating system and compiler. If we are using a command-line interface in a unix system we can compile it as follow:
$ g++ -o sum sum.cpp
Where -o is an argument to te compiler and names the file in which to put executable file. This command generates an executable file named sum
, to execute in the current directory:
$ ./sum
Let’s consider the following example:
#include <iostream>
int main()
{
std::cout << "Enter two numbers" << std::endl;
int v1=0, v2=0;
std::cin >> v1 >> v2;
std::cout << "The sum of " << v1 << " and " << v2 << " is " << v1 + v2 << std::endl;
return 0;
}
iostream is a standard library that provides IO objects. To handle an input, we use an object cin
(istream), for output we use an cout (ostream).
- The first line tells the compiler that we want to use
iostream
library. - The first statement in the body of main executes an expression.
std::cout << "Enter two numbers" << std::endl;
- The
<<
operator takes two operands: The left-hand operand must be anostream
object, the right operand is a value to print. - The
endl
is a special value called manipulator. Writtingendl
has the effect of ending the current line and flusing the buffer associated with that device. - The prefix
std::
indicates that the namescout
andendl
are defined inside the namespace named std. The namespaces allow us to avoid inadvertent collisions between the names. - The statement
std::cin >> v1 >> v2;
define analogously to the output operator. It takes an istream as its left-hand operand and an object as its right-hand operand. It reads data from the givenistream
and stores what was read in the given object.
HelloWorld
So this is the Hello world example in C++
#include <iostream>
int main()
{
std::cout << "Hello World!" << std::endl;
return 0;
}