Nested function calling and nested definition in C ++

In C ++, nested calls of functions are allowed, but nested definitions of functions are not allowed. For example:

# Include <iostream. h>
Int swpint (int * a, int * B)
{
Int C;
C = *;
* A = * B;
* B = C;
Return;
}
Void main ()
{
Int e = 12;
Int F = 89;
Swpint (& E, & F );
Cout <e <Endl <F <Endl;
}
This definition is correct, but a compilation error occurs if the following definition is used:

# Include <iostream. h>
Void main ()
{
Int e = 12;
Int F = 89;
Int swpint (int * a, int * B)
{
Int C;
C = *;
* A = * B;
* B = C;
Return;
}
Swpint (& E, & F );
Cout <e <Endl <F <Endl;
}

Error c2601: 'swpint': Local function definitions are illegal