Size of an Array

When an array is passed to a function or memory is dynamically allocated, we will lose the size of an array at run-time.

#include <stdio.h>
#include <string.h>

int function ( char *arr)
{
    strncpy(arr, "Shirley", sizeof(arr));
    printf("\n In function, arr size %s",arr);
}
main()
{
    char array[64] = {0};
    int ret =0;
    ret = function(array);
    printf("\n arr size %s",array);
    return;
}

In function, arr size Shir                                       
arr size Shir                                                    
Exited: ExitFailure 15                                           

When you do strncpy, the array size will be pointer size. So, it is good to store the array size somewhere or  use memcpy, instead of strcpy. The good solution is to pass the length of an array along with the array as a separate argument.



#include <stdio.h>
#include <string.h>

int function ( char *arr, int len)
{
    strncpy(arr, "Shirley", len);
    printf("\n In function, arr size %s",arr);
}
main()
{
    char array[64] = {0};
    int ret =0;
    ret = function(array, sizeof(array));
    printf("\n arr size %s",array);
    return;
}

 In function, arr size Shirley                                      
 arr size Shirley                                                   
Exited: ExitFailure 18                                              

This will not give the RETURN_LOCAL warning. Click here for RETURN_LOCAL