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How to return local array from a C++ function?
A local array cannot be directly returned from a C++ function as it may not exist in memory after the function call. A way to resolve this is to use a static array in the function. As the lifetime of the static array is the whole program, it can easily be returned from a C++ function without the above problem.
A program that demonstrates this is given as follows.
Example
#include <iostream> using namespace std; int *retArray() { static int arr[10]; for(int i = 0; i<10; i++) { arr[i] = i+1; } return arr; } int main() { int *ptr = retArray(); cout <<"The array elements are: "; for(int i = 0; i<10; i++) { cout<< ptr[i] <<" "; } return 0; }
Output
The output of the above program is as follows.
The array elements are: 1 2 3 4 5 6 7 8 9 10
Now let us understand the above program.
In the function retArray(), a static array arr is defined. Then a for loop is used to initialize this array. Finally array arr is returned. The code snippet that shows this is as follows.
int *retArray() { static int arr[10]; for(int i = 0; i<10; i++) { arr[i] = i+1; } return arr; }
In the main() function, the function retArray() is called and ptr points to the start of the array arr. The array elements are displayed using a for loop. The code snippet that shows this is as follows.
int main() { int *ptr = retArray(); cout <<"The array elements are: "; for(int i = 0; i<10; i++) { cout<< ptr[i] <<" "; } return 0; }