Does anyone know the difference beetwen "Dediğim" and "dedim"? In case saying "As I said", which one will be the best: Dediğim gibi or dedim gibi?

Thanks in advance!

dediğim gibi is correct because dediğim is a participle > noun/adjective and dedim is a finite verb.

bana yardım ettiğin için çok teşekkür ederim

You should consider the difference of the past simple tense "-di" and the -dik patterns.

"Çabuk ol" dedim. (I said "Be quick!")

Dediğim her şeye inanıyorlar. (They believe in everything I say/said.)

Ne dediğimi anladın mı? (Have you understood what I said?)

de+di(simple past)+m(personal suffix)-->dedim (I said)

de+dik+m---------------------------->dediğim (that I said)

the past simple:

http://www.turkishclass.com/turkish_lesson_269

-dik is a different pattern.

http://www.turkishclass.com/turkish_lesson_299 (nominative)

http://www.turkishclass.com/turkish_lesson_297 (in accusative)

These are enough for now, if you want, you already can look at the others.

But -how can i know this?- if you have a lack of the softening of consonant, [that´s to say: dedik+i--->dediği | k-->ğ] : http://www.turkishclass.com/turkish_lesson_253]