Return an Array in C

by Online Tutorials Library July 14, 2022

Return an Array in C

What is an Array?

An array is a type of data structure that stores a fixed-size of a homogeneous collection of data. In short, we can say that array is a collection of variables of the same type.

For example, if we want to declare ‘n’ number of variables, n1, n2…n., if we create all these variables individually, then it becomes a very tedious task. In such a case, we create an array of variables having the same type. Each element of an array can be accessed using an index of the element.

Let’s first see how to pass a single-dimensional array to a function.

Passing array to a function

  #include <stdio.h>  void getarray(int arr[])  {      printf(“Elements of array are : “);      for(int i=0;i<5;i++)      {          printf(“%d “, arr[i]);      }  }  int main()  {     int arr[5]={45,67,34,78,90};     getarray(arr);     return 0;  }  

In the above program, we have first created the array arr[] and then we pass this array to the function getarray(). The getarray() function prints all the elements of the array arr[].

Output

Passing array to a function as a pointer

Now, we will see how to pass an array to a function as a pointer.

  #include <stdio.h>  void printarray(char *arr)  {      printf(“Elements of array are : “);      for(int i=0;i<5;i++)      {          printf(“%c “, arr[i]);      }  }  int main()  {    char arr[5]={‘A’,’B’,’C’,’D’,’E’};    printarray(arr);    return 0;  }  

In the above code, we have passed the array to the function as a pointer. The function printarray() prints the elements of an array.

Output

Note: From the above examples, we observe that array is passed to a function as a reference which means that array also persist outside the function.

How to return an array from a function

Returning pointer pointing to the array

  #include <stdio.h>  int *getarray()  {      int arr[5];      printf(“Enter the elements in an array : “);      for(int i=0;i<5;i++)      {          scanf(“%d”, &arr[i]);      }      return arr;  }  int main()  {    int *n;    n=getarray();    printf(“nElements of array are :”);    for(int i=0;i<5;i++)      {          printf(“%d”, n[i]);      }      return 0;  }  

In the above program, getarray() function returns a variable ‘arr’. It returns a local variable, but it is an illegal memory location to be returned, which is allocated within a function in the stack. Since the program control comes back to the main() function, and all the variables in a stack are freed. Therefore, we can say that this program is returning memory location, which is already de-allocated, so the output of the program is a segmentation fault.

Output

There are three right ways of returning an array to a function:

Using dynamically allocated array
Using static array
Using structure

Returning array by passing an array which is to be returned as a parameter to the function.

  #include <stdio.h>  int *getarray(int *a)  {          printf(“Enter the elements in an array : “);      for(int i=0;i<5;i++)      {          scanf(“%d”, &a[i]);      }      return a;  }  int main()  {    int *n;    int a[5];    n=getarray(a);    printf(“nElements of array are :”);    for(int i=0;i<5;i++)      {          printf(“%d”, n[i]);      }      return 0;  }  

Output

Returning array using malloc() function.

  #include <stdio.h>  #include<malloc.h>  int *getarray()  {      int size;      printf(“Enter the size of the array : “);      scanf(“%d”,&size);      int *p= malloc(sizeof(size));      printf(“nEnter the elements in an array”);      for(int i=0;i<size;i++)      {          scanf(“%d”,&p[i]);      }      return p;  }  int main()  {     int *ptr;     ptr=getarray();     int length=sizeof(*ptr);     printf(“Elements that you have entered are : “);     for(int i=0;ptr[i]!=’

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Return an Array in C

Return an Array in C

What is an Array?

Note: From the above examples, we observe that array is passed to a function as a reference which means that array also persist outside the function.

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