alternative to ‘-nakereba naranai’

Hi, I have recently encountered a few instances of what I believe to be an alternative phrasing of '-nakereba naranai', which takes the form of '-neba naran', for example 'ikaneba naran'. While the use of the plain negative is vaguely familiar to me, I would like to know if anyone could tell me how commonly this form is used, who would use it, etc. in place of using the more common '-nakya'. Thanks in advance.

- ikanakereba naranai

- ikanai to naranai

- ikanakya naranai

- ikaneba naranai
- ikaneba naran

...are all variants of "I must go." (You could also replace the "naranai" with "ikenai" as well.)

The one you asked about, "ikaneba naran," is not really used in everyday speech, but you might hear this in movies (ol' times), coming from samurais, or middle-aged male characters, who would use this phrasing to emphasize his detemination and firm resolve (no matter what others around him might say about this, he MUST go, kind of feeling).

In contrast, "ikanaito (naranai)" or "ikanakya naranai" would be something you hear in real life :)

...also this "ikaneba naran!" could be used as a firm order by a male character to his subordinate(s). Again, this has this tone of firmness that noone can refuse.

ikanai to ikenai is what a japanese friend told me to use after I struggled a few times with the -nakereba naranai form. :)

Ah, I see. Thank you for your answers. One other thing, is the use of '-naito ______' exactly equivalent to 'nakereba naranai' and its variants? I often find myself using '-nai to__' and only afterwards thinking perhaps I should have used the other...

One other thing, is the use of '-naito ______' exactly equivalent to 'nakereba naranai' and its variants?

I asked my japanese teacher yesterday specifically about the difference between 'nakereba naranai' and 'nai to ikemasen' and she told me that the latter one is a bit more casual. If you use ikenai insted of ikemasen, then it is of course again more casual.

So for talking to your boss or other much higher persons, you should probably use the 'nakereba naranai' form, otherwise the 'nai to ikemasen' should be sufficient according to my teacher.

"--nai to ikenai/ ikemasen" is definitely the more casual one. My Japanese friends often leave off the last word and just say something like "Kaeranai to" or "Ikanai to"- the ikenai part is understood by the listener. Same with people just saying "Ikanakya".