I was reading on misra website that for assigning 0 to unsigned variable, 'u' must be suffixed.

For example:

uint8_t my_cnt = 0U;

1. Does that even on declaring array I should use this.Like

uint8_t my_arr[10U];

2. Also while using switch cases like:

void func(uint8_t no)
{
    switch(no)
    {
         case 1U:
         break;

         case 2U:
         break;

    }
}

If yes then what if variable passed to switch is of int8_t type. In above example if

int8_t no;

 

0 is a 0 is a 0. The U just tells the compiler that this number has to be unsigned. The compiler will determine what representation (and size) is required to match the implied number.

In other words, it isn't necessary to put something like

 uint8_t x;
 if (x == 1U)
    break;

unless your compiler is trying to use a signed number where an unsigned is needed (which would be very rare - and almost always result in a warning).