http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-103131.php

Wanna Gotta Gonna

1. Want to = WANNA

• I want to go out = I wanna go out

    He wants to go out   

• Does he want to go out = Does he wanna go out ?

2. Have got to = GOTTA

• I have got to go out = I gotta go out 

        He has got to do something = He gotta do something
        I have to work = I gotta work
3. Going to = GONNA

• I'm going to eat = I'm gonna eat

    What are you going to do ? = What (are) you gonna do ?

GOTTA
Have got a:  
‘I gotta car.’
Have got to:

‘you gotta be careful’