C++ Returning Pointer from Functions
In the previous chapter, we learned how to return an array from a function in C++. Similarly, C++ allows you to return a pointer from a function. To do this, you must declare a function that returns a pointer, as follows:
int * myFunction()
{
.
.
.
}
Additionally, C++ does not support returning the address of a local variable outside the function, unless the local variable is defined as a static variable.
Now, let's look at the following function, which generates 10 random numbers and returns them using an array name that represents a pointer (i.e., the address of the first array element), as follows:
Example
#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;
// function to generate and return random numbers
int * getRandom( )
{
static int r[10];
// Set seed
srand( (unsigned)time( NULL ) );
for (int i = 0; i < 10; ++i)
{
r[i] = rand();
cout << r[i] << endl;
}
return r;
}
// main function to call the function defined above
int main ()
{
// a pointer to an integer
int *p;
p = getRandom();
for ( int i = 0; i < 10; i++ )
{
cout << "*(p + " << i << ") : ";
cout << *(p + i) << endl;
}
return 0;
}
#include <ctime>
#include <cstdlib>
using namespace std;
// function to generate and return random numbers
int * getRandom( )
{
static int r[10];
// Set seed
srand( (unsigned)time( NULL ) );
for (int i = 0; i < 10; ++i)
{
r[i] = rand();
cout << r[i] << endl;
}
return r;
}
// main function to call the function defined above
int main ()
{
// a pointer to an integer
int *p;
p = getRandom();
for ( int i = 0; i < 10; i++ )
{
cout << "*(p + " << i << ") : ";
cout << *(p + i) << endl;
}
return 0;
}
When the above code is compiled and executed, it produces the following result:
624723190 1468735695 807113585 976495677 613357504 1377296355 1530315259 1778906708 1820354158 667126415 *(p + 0) : 624723190 *(p + 1) : 1468735695 *(p + 2) : 807113585 *(p + 3) : 976495677 *(p + 4) : 613357504 *(p + 5) : 1377296355 *(p + 6) : 1530315259 *(p + 7) : 1778906708 *(p + 8) : 1820354158 *(p + 9) : 667126415other extensions