Which one to use??

Question

I can't tell him.

No puedo decirle or no le puedo decir ?

Is there a rule for that ?

Thanks in advance

Answer 1

attaching pronouns to infinitves

They are cases where one is required over the other, but I need to find the source that I once read that explains when.

In some cases, attaching the pronoun to the verb is optional.

y

In some cases, it is possible, but not required, to shift the object pronoun to the verb that comes before the infinitive. In the following examples, the two Spanish sentences have basically the same meaning:

but,

However, the pronouns can't be shifted before the main verb in all circumstances, and the list of verbs where shifting is allowed is somewhat arbitrary. For the beginning student, attaching the pronoun to the infinitive is usually the safer choice.

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Ah! Here is one exception (beside regional preferences)

When an infinitive is used as a noun — such as when it follows a preposition or is used as the subject of a sentence — attachment of the pronoun is required:

• Conocerte es amarte. (To know you is to love you.)
  • Una manera muy simple de comprenderlo es observarlo. (A very simple way of understanding it is to observe it.)
  • Pulsa sobre la fotografía para verme con mi nueva familia. (Click on the photograph to see me with my new family.)

Muy bien explicado. - Jubilado, Dec 6, 2011

Answer 2

¿No puedo decirle or no le puedo decir?

Both are correct.