Creating functions in C++
Functions allow to structure programs in segments of code to perform individual tasks.
In C++, a function is a group of statements that is given a name, and which can be called from some point of the program. The most common syntax to define a function is:
type name ( parameter1, parameter2, ...) { statements }
Where:
– type
is the type of the value returned by the function.
– name
is the identifier by which the function can be called.
– parameters
(as many as needed): Each parameter consists of a type followed by an identifier, with each parameter being separated from the next by a comma. Each parameter looks very much like a regular variable declaration (for example:int x
), and in fact acts within the function as a regular variable which is local to the function. The purpose of parameters is to allow passing arguments to the function from the location where it is called from.
– statements
is the function’s body. It is a block of statements surrounded by braces { } that specify what the function actually does.
|
The first result is 5 The second result is 5 The third result is 2 The fourth result is 6 |
Calling functions in C++
#include <iostream>
using namespace std;
int addition (int a, int b)
{
int r;
r=a+b;
return r;
}
int main ()
{
int z;
z = addition (5,3);
cout << "The result is " << z;
}
This program is divided in two functions: addition
and main
. Remember that no matter the order in which they are defined, a C++ program always starts by calling main
. In fact, main
is the only function called automatically, and the code in any other function is only executed if its function is called from main
(directly or indirectly).
In the example above, main
begins by declaring the variable z
of type int
, and right after that, it performs the first function call: it calls addition
. The call to a function follows a structure very similar to its declaration. In the example above, the call to addition
can be compared to its definition just a few lines earlier:
The parameters in the function declaration have a clear correspondence to the arguments passed in the function call. The call passes two values, 5
and 3
, to the function; these correspond to the parameters a
and b
, declared for functionaddition
.
At the point at which the function is called from within main, the control is passed to function addition
: here, execution of main
is stopped, and will only resume once the addition
function ends. At the moment of the function call, the value of both arguments (5
and 3
) are copied to the local variables int a
and int b
within the function.
Then, inside addition
, another local variable is declared (int r
), and by means of the expression r=a+b
, the result of a
plus b
is assigned to r
; which, for this case, where a
is 5 and b
is 3, means that 8 is assigned to r
.
Hi guys this mastery is about importing libraries. Every time that we create a new pogram we need declarate libraries e.g.:
Libraries haves a lot of functions made, and every librarie have ther own utilities.
Basicly to declare a library we need to put in the star of program like this:
#include <iostream> (thos is to make an input and an output)
#include <cstdlib>
#include <ctime>(this we used for an activity for random numer)
This webpage have a lot of libraries and references is very useful.
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