I’ve no idea

Okay how about contraction followed by "to"?
For example:
"I've to go",
"You've to do it"

Sorry for having to write another thread but I just thought of more examples, like how about if its followed by an article and a noun: "I've a headache". Or just a noun for that matter: "I've food in the bag". I feel inclined to believe that these are wrong and that there should be a good basis on it's syntax somewhere, but I can't find it. I just want to show it to some friends who keep using that kind of syntax.

My grandfather, when forced by the Commonwealth of Pennsylvania to adorn his car with a license plate that had the motto "You've got a friend in Pennsylvania", took out a paint can and painted over the "got". QED.

None of the examples you've given is wrong. You're probably just not used to hearing them. "I've an idea" is very common in my experience. "I've to go" is much less common (again, in my experience, although it's not totally unfamiliar to me), but "I've" is, after all, just an abbreviation of "I have."

Give those poor friends a break.

I can't think of a reason why "I've to go" is wrong but I don't hear it and wouldn't say it. Soothfast, it's hard to say "I've to go" without saying "I hav to go" and that's likely why one doesn't hear it. "I've to go" doesn't flow and speaking a tung is about making the words flow together. So while it isn't wrong grammatically, it isn't said.

Aside from that the "have to" idiom that is usually said with emphasis so it loses it emphasis if yu try to contract it.

Euphony... just euphony. That's the difference. one is pleasant and one is not. Similar to "A History of..." and "An Historical Account".

1. "Is it a correct syntax to say: 'I’ve no idea' to shortcut 'I have no idea? I see alot of people doing this and I feel that it is wrong."

I've no idea why you'd have trouble with it. It is perfectly fine English and completely unremarkable.

2. On "I've to go", I wondered: is this a BE usage? To me, (as a Canadian English speaker), it desperately needs either "got" in there or "have" in full to give it emphasis. Now, if the statement were extended e.g., "I've to go to the school tonight", I could certainly see that as a BE usage, though I would say "I've got to go to the school tonight."

Do any UK posters have thoughts on this?

I admit I was a little fast on the trigger eventhough I was the one with the wrong information. I live in a country where English isn't the primary language so if these usages sound weird to you, they sound even weirder to me. Thank you for your responses, they really opened my eyes.

"I live in a country where English isn't the primary language so if these usages sound weird to you, they sound even weirder to me."

Not a problem, Ramon. Many constructions that native speakers take for granted can strike you as very odd when you do examine them closer.

A good example is something like "I had better go home" which can be very perplexing to a non-native English speaker when first encountered.

Even more perplexing in its elliptical form: "I better go home"!

With 'have (got) to', it seems to me to depend on the surrounding words. I (BrE) am more likely to say I've got to go', than 'I've to go', but 'I've to be there at eight' sounds fine.

Similarly I'm probably more likely to say 'I've got an idea' than 'I've an idea', but conversely, 'I've no idea' rather than 'I've got no idea'. It just depends how it trips off the tongue.

The number of Google hits for each of the phrases I've mentioned seem to suggest that my instincts are reasonably correct. 'I've got a headache', for example, gets more than 10 times the number of hits on Google as 'I've a headache'.

I agree with Aaa

1. The apostrophe indicates a contraction - missing letters - and is legitimate. It reflects what's actually said, in this case, when a verbal shortcut is used. It was used much more often in the past, commonly in the middle of frequent or long words, as a kind of shorthand. Also shows how the language is continuing to evolve. In recent memory, we have dropped the apostrophe in 'till (contraction of until) because it's become a recognised legitimate word.

PS - your spellchecker doesn't like the English spelling of recognised and is insisting on a 'Z' !!

2. Got is technically incorrect but accepted. it's passed into normal use. I won't expand.

'I've no idea' is fine because there is no emphasis on 'have'.
'I've to go' doesn't work because you need emphasis on the 'have' to express an obligation.

Thank you for your post, Ramon. Non-native speakers can produce some surprising perspectives.

How about these two complete, unconventional sentences spoken by B:

A: Will you meet me for coffee?
B: I'll.
A: Are you hungry?
B: I'm.
A: Okay, let's have lunch instead.

Interesting, Partial.
Perhaps it's a question of the distinction between a main verb and an auxiliary verb.
Chambers describes the latter as 'a verb that helps to form the mood, tense or voice of another verb'.
Verbs such 'have' and 'be' can be either main verbs or auxiliary verbs depending on the context. The 'will' in 'I will go' is an auxiliary verb and can be contracted but in the examples you have given, Partial, they are main verbs and can't be contracted.
Okay, shoot me down.

@Skeeter Lewis - interesting point about stress, but I can't really see any difference in stress between "I have to be there at eight" and "I have to go now", where I would suggest that the stress is usually on the main verb in both examples - "be" and "go". Wouldn't we only stress "have" if we were emphasising how important it was?

Yet for me, "I've to be there at eight" works, but "I've to go now" doesn't really.

But in any case, as I said above, I'd use "have got to" in the second anyway, then there's no problem: "I've got to go now".