difference between 1:10 and c(1:10)

Question

I understand that c is used to combine elements. But what is the difference between 1:10 and c(1:10)? I see that the outputs are the same. Shouldn't c(1:10) give an error, because 1:10 already combines all the elements?

> 1:10
 [1]  1  2  3  4  5  6  7  8  9 10
> c(1:10)
 [1]  1  2  3  4  5  6  7  8  9 10
> class(1:10)
[1] "integer"
> class(c(1:10))
[1] "integer"

Answer 1

If you combine (aka c function) with only one parameter it is the same as the identity (aka not calling the c function). Therefore c(1:10) is the same as 1:10. However you can combine with as many arguments as you want with different type (character,number...). It will convert the type for you.

 all.equal(1:10,c(1:5,6:10))

[1] TRUE

all.equal("meow",c("meow"))

[1] TRUE

c(1:5,6:10,"meow")

[1] "1"    "2"    "3"    "4"    "5"    "6"    "7"    "8"    "9"    "10"   "meow" 

class(c(1:5,6:10,"meow"))

[1] "character"

Another difference is that you can call c with the parameter recursive. As the doc states:

?c

Usage

c(..., recursive = FALSE)
Arguments

... 
objects to be concatenated.

recursive   
logical. If recursive = TRUE, the function recursively descends through lists (and pairlists) combining all their elements into a vector.