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What is the difference between Mandarin and Shanghaiese?

the difference between Mandarin and Shanghaiese is just as American English and the British English

There are a lot of different on pronunciation.For example:
我们出去玩玩好吗?
Mandarin: WO MEN CHU QU WAN WAN HAO MA?
Shanghaiese: A LA CE QI BER XIANG XIANG HAO VA?

you can say mandarin wherever in China,almost everyone can understand.shanghaiese only can be used in shanghai or area nearly.and pronunce or characters are different
for example:I=我（mandarin:wo）＝阿拉(shanghaiese:a la)，you =你（mandarin:ni）＝侬 (shanghaiese:nong)

so different of them , if we wanna to know what they say , we need to learn as well, it's hard work.

shanghaiese is a kind of chinese dialect.don't worried,study mandarin(谱通话）well is ok

sorry ,i want to say普通话

Mandarin and shanghaiese is difference in pronounce.

They are different regions' languages. Mandarin , it means standard chinese. shanghaiese,is a kind of chinese,sounds like different. you'd better study Mandarin,because in our country,in China,Bureau of Culture advocates speaking it.

Hi.Eric!Long time no see.Let me help you.
Mandarin of Chinese is Putong hua.普通话.Shanghaiese is a locality Chinese.Both use the same Chinese characters.But the pronunciation is have many differences.China is too large.So it has too many locality languages.Most of them are Chinese.Few of them are other languages.For example:Mongolian.I don't kown how to say Shanghaiese.But I can say ChangShaese.(ChangSha is the capital city of Hunan province)."Have no sth"in Chinese is 没xxx,the pinyin is "mei you shen me"But in Changshaese we read it "mao ".If you have any questions,you can tell me.
And pleaese tell me are there any mistakes is my anwser?

Mandarin is the official language in China. You can speak Mandarin to any people of Chinese. Shanghaiese is just only a local dialect in Shanghai and only used by Shanghaiese. To the people live in the other part of China, Shanghaiese is like something of foreign languages.

hi, dear Eric, long time no see. There is a good introduction of Mandarin: http://en.wikipedia.org/wiki/Mandarin_(linguistics)
As regards the Shanghaiese, it's one of the dialects in China and be used in Shanghai.The development of Shanghaiese is affected by Jiaxingese() and Suzhouese. Jiaxing locates in Zhejiang and Suzhou is in Jiangsu, but both are near Shanghai.

Mandarin is a language which every Chinese can understand. In China everyone should study it. But shanghaiese is a local language, if you can understand Mandarin,you just can understand a little Shanghaiese if they speak slowly.

don't need to learn shanghaiese, mandarin is useful enough

The difference between Mandarin and Shanghaiese is that:
one can be understood by all chinese
one can be only understood by the people in shanghai.

Those are different in Pronunciation and Feeling...
If you can say Mandarin,and you can go everywhere in chia...