declares an automatic variable
Management type and size variables are automatic, no statement is, in principle, necessary.
Their visibility and permanence can be:
Automatic (no statement)
It is known that within the function where it is defined (without declaration), and it is lost output.
See also:
Statement:
static x;
It is known that within the function where it is defined and retains its value.
Statement:
extern x;
It is known wherever it is so declared.
Statement:
globale x;
It is known in all program functions defined on an object and unknown to the outside.