Why is goto poor practise? [duplicate]

Answer 1

In some cases it makes sense. But, in the majority of cases use of it it considered poor practice because it can make the execution path of code tricky to read compared to using structured code such as for loops and while loops.

When you look at a goto or a label, you don't really know where is goes to or comes from without reading or searching through the code for the label name. This is tricky especially if the goto doesn't fit on the same screen as the label. Compare this to a for loop or a while loop or an if.. you can tell from the structure (i.e. indenting of the code) what the execution path is.

Having said this, it sometimes is useful, especially for example when jumping out of some nested for loops that are digging for a particular value inside a multi-dimensional array. You could use a goto here to jump out of the for loops when the correct value is found.

Answer 2

Because the structure of the code can be difficult to follow.

This

y:
// do more stuff
goto x

p:
// do stuff
// then done
goto y;

x: 
  // do a bunch of stuff
  if (...)
      goto y;
  else
      goto p;

done:

is much less clear than

int main()
{
    x();
}


function p()
{
    if (...)
    {
         return;
    }
}


function x()
{
    if (...)
    {
         return;
    }
    else 
    {
         p();
    }
}