C++ arrays and functions

In this article, you will learn to pass arrays to C ++in the function. You will learn how to pass one-dimensional and multi-dimensional arrays.

arraycan be passed as a parameterFunction. It is also possible to return an array from the function. Consider the following example, passing a one-dimensional array to a function:

Example1Passing a one-dimensional array to a function

C ++The program displays the scores by passing a one-dimensional array to the function.5scores of students.

#include <iostream>
using namespace std;
void display(int marks[5]);
int main()
{
　　　　int marks[5]= {88,　76,　90,　61,　69});
　　　　display(marks);
　　　　return 0;
}
void display(int m[5])
{
　　　　cout << "Display scores: "<< endl;
　　　　for (int i = 0; i <　5;　++i)
　　　　{
　　　　　　　　cout << "Student " << i　+　1　<<": "<< m[i] << endl;
　　　　}
}

Output result

Display scores:　
Student　1:　88
Student　2:　76
Student　3:　90
Student　4:　61
Student　5:　69

When an array is passed as a parameter to a function, only the array name is used as a parameter.

display(marks);

It should also be noted the difference between passing an array as a parameter and passing a variable.

void display(int m[5]);

The parameter marks in the above code represents the array marks[5] in the function declaration.

The memory address of the first element in the form parameter int m [5] converted to int * m; The pointer points to the same address pointed to by the array marks.

This is the reason, although the function is used with a different array name m[5perform operations, but the original array is still being operated on in marks.

C ++This way of handling passing arrays to functions saves memory and time.

Pass multi-dimensional array to function

Multidimensional ArraysMulti-dimensional arrays can be passed in a manner similar to one-dimensional arrays. Consider the following example, passing a two-dimensional array to a function:

Example2: Pass multi-dimensional array to function

C ++The program displays the array by passing the elements of the two-dimensional array to the function.

#include <iostream>
using namespace std;
void display(int n[3][2]);
int main()
{
　　　　int num[3][2]= {
　　　　　　　　{3,　4},
　　　　　　　　{9,　5},
　　　　　　　　{7,　1}
　　　　});
　　　　display(num);
　　　　return 0;
}
void display(int n[3][2])
{
　　　　cout << "Display value: " << endl;
　　　　for (int i = 0; i <　3;　++i)
　　　　{
　　　　　　　　for (int j = 0; j <　2;　++j)
　　　　　　　　{
　　　　　　　　　　　　cout << n[i][j] << " ";
　　　　　　　　}
　　　　}
}

Output result

Display value:　
3　4　9　5　7　1

In the above program, the multi-dimensional array num is passed to the function display().

In the display() function, use nested for loops to traverse the array n (num).

This program uses2timesfor loopTraverse the elements in the two-dimensional array. If it is a three-dimensional array, then you should use3 for loop.

Finally, all elements are printed to the screen.

Note:　dimensions greater than2Multi-dimensional arrays can be passed in a manner similar to two-dimensional arrays.

C++ Returning an array from a function

C++ It is not allowed to return a complete array as a function parameter. However, you can return a pointer to an array by specifying the array name without an index.

If you want to return a one-dimensional array from a function, you must declare a function that returns a pointer, as follows:

int　*　myFunction()
{
.
.
.
}

Additionally, C++ It is not supported to return the address of a local variable outside the function unless the local variable is defined as static variable.

Now, let's look at the following function, which will generate 10 a random number, and use an array to return them, as follows:

#include <iostream>
#include <cstdlib>
#include <ctime>
　
using namespace std;
　
//　Function to generate and return random numbers
int　*　getRandom()
{
　　static int r[8];
　
　　//　Set seed
　　srand((unsigned)time(NULL));
　　for (int i = 0; i <　8;　++i)
　　{
　　　　r[i] = rand();
　　　　cout << r[i] << endl;
　　}
　
　　return r;
}
　
//　the main function to call the above-defined function
int main ()
{
　　　//　a pointer to an integer
　　　int　*p;
　
　　　p = getRandom();
　　　for ( int i = 0; i <　8; i++　)
　　　{
　　　　　　　cout << \*(p　+　<< i << ") : ";
　　　　　　　cout <<　*(p　+　i) << endl;
　　　}
　
　　　return 0;
}

When the above code is compiled and executed, it will produce the following results:

30737
23110
21765
14820
8295
12330
28395
191
*(p　+　0) : ;　30737
*(p　+　1) : ;　23110
*(p　+　2) : ;　21765
*(p　+　3) : ;　14820
*(p　+　4) : ;　8295
*(p　+　5) : ;　12330
*(p　+　6) : ;　28395
*(p　+　7) : ;　191