goto crosses initialization [duplicate]

Answer 1

You can't jump over initialization of an object.

size_t i = 0; 

is an initialization, while

size_t i;
i = 0;

is not.

The C++ Standard says:

It is possible to transfer into a block, but not in a way that bypasses declarations with initialization. A program that jumps from a point where a local variable with automatic storage duration is not in scope to a point where it is in scope is ill-formed unless the variable has POD type (3.9) and is declared without an initializer.

Answer 2

The reason for the rule is that jumping over an initialization leaves the object in an undefined state. When you get to the end of the function, destroying those uninitialized objects might not work.

One exception is obviously that

int   i;

leaves the int uninitialized anyway, so skipping that is just half bad.

If you want to leave a function early, a quick return is an option to avoid the goto.