Question

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What is useful about this C syntax?
C variable declarations after function heading in definition
What weird C syntax is this?

I’m trying to understand some code and it has something like the following:

int getr(fget)
FILE *fget;
{
   /* More declarations and statements here */
   return (1);
}

Is there any difference between the above and:

int getr(fget)
{
   FILE *fget;
   /* More declarations and statements here */
   return (1);
}

If so, how do they differ?

Answer 1

Both functions are declared in the old-style (non-prototype) form. Old-style function declarations are obsolescent in the current C standard and their use is strongly discouraged by the C Standard.

In the second form there is no mention of the fget parameter type which is assumed to be an int. Then another object fget of type FILE * is declared and it shadows the parameter variable with the same name.

With gcc the -Wshadow warning option would get you a warning in your second example because of the shadowing of the parameter:

   -Wshadow
       Warn whenever a local variable shadows another local variable, 
       parameter or global variable or whenever a built-in function is shadowed.