Looping over a set of standardized files to collect information and save it in a different files

I have several files in a folder. They all have same layout and I have extracted the information I want from them.

So now, for each file, I want to write a .csv file and name it after the original input file and add "_output" to it.

However, I don't want to repeat this process manually for each file. I want to loop over them. I looked for help online and found lots of great tips, including many in here.

Here's what I tried:

#Set directory
dir = setwd("D:/FRhData/elb") #set directory
filelist = list.files(dir) #save file names into filelist

myfile = matrix() 
#Read files into R
 for ( i in 1:length(filelist)){
  myfile[i] = readLines(filelist[i]) 

         *code with all calculations*

   write.csv(x = finalDF, file = paste (filename[i] ,"_output. csv" 
    ,sep = ";")
 }    

Unfortunately, it didn't work out. Here's the error message I get:

Error in as.character(x) : cannot coerce type 'closure' to vector of type 'character'

In addition: Warning message: In myfile[i] <- readLines(filelist[i]) : number of items to replace is not a multiple of replacement length

And 'report2016-03.txt' is the name of the first file the code should be executed on.

Does anyone know what I should do to correct this mistake - or any other possible mistakes you can foresee?

Thanks a lot.

====================================================================== Here's some of the resources I used:

https://www.r-bloggers.com/looping-through-files/

How to iterate over file names in a R script?

Looping through files in R

Loop in R loading files

How to loop through a folder of CSV files in R