What is the difference between local variables auto int a and int a?

Question

Use case of storage class identifier auto?I understand that all local variables are auto by default. But whats makes difference by writing explicitly auto int a ?

Answer 1

There is strictly no difference.

{
   auto int a;
   /* ... */
}

and

{
   int a;
   /* ... */   
}

are equivalent.

The common practice is not to put the auto specifier.

Answer 2

There are two possible cases:

1. auto is the default, and explicitly adding the keyword accomplishes nothing
2. auto isn't allowed (e.g., on a global variable) in which case adding auto prevents the code from compiling