Yet another way to say to have to do 〜 or must do 〜 is with the expression 〜なくちゃ. This is a more casual way of speaking, used among friends or people of the same age or rank. Apart from this, it has the same meaning as 〜なくて は いけません and its variants.
〜なくちゃ can be used by itself, or it can be followed by ダメ, いけない or ならない, each one being slightly more formal than the other, though using 〜なくちゃ is never as formal as using 〜なくては。。。.
|I have to read this book.
|この 本 を 読まなくちゃ。kono hon o yomanakucha.
|I have to call him.
|彼 に 電話しなくちゃ ダメ。kare ni denwashinakucha dame.
|I need to go to the hospital.
|病院 に 行かなくちゃ いけない。byouin ni ikanakucha ikenai.
|I must buy new shoes.
|新しい 靴 を 買わなくちゃ ならない。atarashii kutsu o kawanakucha naranai.