Issues in pointer to char* value

What is the issue with this code (It is printing arr[0] correctly but I am getting issues with arr[1]... printing some weird characters):

using namespace std;
char ** setName() {
    char * arr[2];
    for (int i=0;i<2;i++)
       arr[i] = (char*)malloc(100);
    arr[0] = strdup("Robert");
    arr[1] = strdup("Jose");
    return arr;
}
int 开发者_Python百科main()
{
    char **arr;
    arr = setName();
    printf("First name is %s\n", arr[0]);
    printf("Second name is %s\n", arr[1]);
    return 0;
}

If it matters, i am running this code in Windows using Visual Studio 8.

You have two problems in that code:

1. An auto array such as your char * arr[2] is not automatically created with new[]; its storage goes away when the function returns. This is the source of your garbage. You should malloc() or new[] it.

   char **arr = malloc(2 * sizeof (*char));
   

2. strdup() does a malloc(), so you are pointlessly malloc()ing storage that is then lost because you overwrite the pointer.

You are returning the address of a local variable. arr doesn't exist after setName exits, so main's arr is pointing to bad memory.

You'd be better off writing straight into main's arr by passing it as a parameter to setName:

using namespace std;
void setName(char* (&arr)[2]) {
    for (int i=0;i<2;i++)
       arr[i] = (char*)malloc(100);
    arr[0] = strdup("Robert");
    arr[1] = strdup("Jose");
}
int main()
{
    char * arr[2];
    setName(arr);
    printf("First name is %s\n", arr[0]);
    printf("Second name is %s\n", arr[1]);
    return 0;
}

Your array of pointers is local to your setName function.

Try something like:

char ** setName() {
  char ** arr = (char **)malloc(2 * sizeof(char *));
  for (int i=0;i<2;i++)
    arr[i] = (char*)malloc(100);
  strcpy(arr[0], "Robert");
  strcpy(arr[1], "Jose");
  return arr;
}

... and don't forget to free what you malloc.

You're returning the address of arr. This is undefined behavior and you really don't know what's going to happen. I would strongly suggest you add a parameter to that function by reference and just pass arr to it from main instead of returning.

Your code can be something like this:

    char *setName() {
        char * arr[2];
        static int j=0;
        int i=0;
        for (i=0;i<2;i++)
            arr[i] = (char*)malloc(100);
        strcpy(arr[0],"Robert");
        strcpy(arr[1],"Jose");
        return arr[j++];
    }

    int main(){
        char *arr1,*arr2;
        arr1 = setName();
        arr2 = setName();   
        printf("First name is %s\n", arr1);
        printf("First name is %s\n", arr2);
        return 0;
    }