Does Spanish use a case system?
The case system technically exists in many languages but it doesn’t always change the form of the nouns or adjectives like it would in English, German, Latin, or Russian.
But you can clearly see how something would adhere to the cases in Spanish:
Is technically accusative where the lo implies a direct object. The lo is just a placeholder for a masculine noun so…
Tengo el pan. - I have the bread.
…Has no change to the article el or the noun.
Where you see the change is in the yo, tú, nosotros and vosotros when they’re direct object markers…
Nosotros/Nosotras queremos… - We want…
Vosotros/Vosotras queréis… - You all want…
Me quieres. - You love me.
Nos quieres. - You love us.
Os quiero. - I love you all.
Another example would be…
A ella is technically the dative case, meaning “to or for whom” but the ella doesn’t change
But then again there’s a difference with yo, tú, nosotros, vosotros and then there’s le and les.
Te doy… - I give you… | (Te) Doy a ti… - I give to you…
Me das… - You give me… | (Me) Das a mí… - You give to me…
Nos das… - You give us… | (Nos) Das a nosotros… - You give to us…
Os doy… - I give you all… | (Os) Doy a vosotros… - I give to you all…
Where it gets weirder is the le and les because you don’t really need it, but you can have it, or not have it, or have it PLUS the a to be emphatic because le and les are used for the recipient but are unisex.
Doy a Ana… - I give to Ana…
Doy a Marco… - I give to Marco…
Le doy a Ana/ella… - I give to Ana/her…
Le doy a Marco/él… - I give to Marco/him…
Doy a Ana y Marco… - I give to Ana and Marco…
Les doy a ellos… - I give to them (at least one male)… [Emphatic]
Doy a Ana y Luisa… - I give to Ana and Luisa…
Les doy… - I give to them…
Les doy a ellas… - I give to them (female)… [Emphatic]
*Note: Whether or not a person tends to use lo/la or le/les is a bit of a regional thing. Some people write Le quiero others write lo/la quiero.
In general, no. Spanish doesn’t really adhere to the case system. When it does, it’s primarily nominative, accusative or dative and only really with the pronoun or object markets.
Regular nouns only change by gender or plural and not the case.
El perro va. - The dog goes.
Doy el perro. - I give the dog.
Doy la pelota al perro. - I give the ball to the dog.
Doy el perro a Ana. - I give the dog to Ana.
[The perro never changes; all that changes is the a / al [a + el] which is indicative of motion “to”]