clearing a char array c

Question

I thought by setting the first element to a null would clear the entire contents of a char array.

char my_custom_data[40] = \"Hello!\";
my_custom_data[0] = \         


        

Answer 1

Use:

memset(my_custom_data, 0, sizeof(my_custom_data));

Or:

memset(my_custom_data, 0, strlen(my_custom_data));