How can I decide when to use “for” + “-ing” or “to” + [infinitive] in a sentence?

Question

Example:

I have nothing to do for now.

Nothing for doing for now.

Another one:

I have some things to study.

I have some things for studying.

New Examples: (QUESTION UPDATED)

I don't know if you use XXX, but I was wondering if it could be useful for sharing knowledge among us.

I don't know if you use XXX, but I was wondering if it could be useful to share knowledge among us.

Another one:

So, we could create a group to share any kind of technology knowledge.

So, we could create a group for sharing any kind of technology knowledge.

Answer 1

This is a very good explanation of the distinction; I have included it reformatted below:

For + -ing: function

We use for + the -ing form of a verb to talk about the function of something or how something is used:

I need something for storing CDs.
The PC is still the most popular tool for developing software systems.

For + -ing: reason

We use for + the -ing form of a verb to refer to the reason for something:

You should talk to Jane about it. You know, she’s famous for being a good listener. (A lot of people know she’s such a good listener.)

For + -ing or to + infinitive?

Warning: We don’t use for + -ing to express our purpose or intention. We use to + infinitive:

We’re going to Lisbon to visit my aunt.
NOT: We’re going to Lisbon for visiting my aunt. or … for visit my aunt.
He’s now studying to be a doctor.
NOT: He’s now studying for to be a doctor. or … for being a doctor.
There’ll be sandwiches to eat and juice to drink.
NOT: There’ll be sandwiches for eat and juice for drink.

I am, however, inclined to disagree with the phrasing of the warning a little, and would phrase it as

Warning: We don't use for + -ing to express an aim or intention. We use to + infinitive.

"Purpose" is a poor choice of words to use in this warning. As you might notice in the first example that this passage offers,

I need something for storing CD's.

is a perfectly fine phrase, and does imply the purpose of needing said "something". Here, you can also substitute to <infinitive> because there is an associated aim/intention:

I need something to store CD's.

In the second example, however:

The PC is still the most popular tool for developing software systems.

a substitution with to develop doesn't work because the PC is not the agent which develops software systems, but the agent used to develop software systems. As such, an appropriate rephrasing would be:

The PC is still the most popular tool used to develop software systems.

And because this remains a statement of purpose, you can also say:

The PC is still the most popular tool used for developing software systems.

I should note that I now rescind my recommendation of the for the purpose of substitution test that I initially suggested in comments on the original post; although that was what I immediately thought of, it is in no way a comprehensive test nor definitive. For instance, it fails in the "for being" example and the "for visiting" examples.

Answer 2

I have nothing to do for now.

Is correct.

Nothing for doing for now.

Is incorrect.

I have some things to study. I have some things for studying.

Both are correct. I will explain.

Using '-ing' is a common problem because it has more than one usage in English, and in other languages it doesn't (Spanish, Portuguese, etc.). For your sake I'll compare it to Portuguese because you're from Brazil.

Here are the two ways you could use '-ing':

1- I am running. ("Running" is a conjugated verb. "Correndo" como "Eu estou correndo". A conjugação chamado o gerúndio.)

2- Running is a great sport. ("Running" is a noun that refers to the activity in general. "A atividade de correr" como "Correr é um grande esporte". Aqui, não é um conjugação ainda que tem '-ing'.)

Those are the two ways we use '-ing' in English, which is different than Portuguese.

In English, you can only use 'for' + '-ing' with the second usage of '-ing'. That's the reason that...

I have some things for studying.

...is correct. "Studying" here is a noun referring to the activity in general, "A atividade de estudar".

The sentence...

I have some things to study.

...is also correct. "Study" here is a verb, "estudar".

Nothing for doing for now.

...is wrong for many reasons. First, because it's missing a verb. Second "For doing" is correct, but no one uses it alone like that, and so it seems very wrong to us. Never use "for doing" alone. Only if you will say something like "for doing homework". I imagine you wanted "There is nothing to do for now".

Now, I will explain the difference between 'for' + '-ing' and 'to'.

'For' + '-ing' means 'For the purpose of... ____-ing'

You will use this when you will follow it with a noun '-ing' word (or a noun phrase).

'to' simply means there's a verb after it.

You will use this when you will follow it with a verb (or a verb phrase).

Final note 'For'+'-ing' is rare, and because of this, it sometimes sounds awkward (esquisito). So only use it if you know it's correct the way you will use it. Otherwise, use 'to'.

Hope that helps.

Answer 3

In this context, “for” is used when stating an intention and “to” is used as a definition of fact.

I have some things to study.

This means you will study and when you do, you will study these things.

I have some things for studying.

This implies that you will study these things, but it could also mean these things help you when studying other things.

The difference becomes more apparent when going from talking about current or future events to talking about past events.

I baked a cake for Gemma, but I gave it to Paul.

In this sentence, Gemma was the intended recipient of the cake, however Paul actually received it.