Looping through all files: "missForest" package in R

Question

Search results for the problem: However I might not apply the solutions correctly.

1. Which is the best method to apply a script repetitively to n .csv files in R?
2. Looping through all files in directory in R, applying multiple commands
3. Looping through all files in a directory in R

My Case I have a folder with hundreds of csv files. I need to run "missForest" package in R to impute missing values. If I run the package for the files one by one I have to do the following:

##change the file name
G1344108 <- read.csv(file.choose(), header = TRUE)

##run missForest with default settings
G1344108.Forest <- missForest(G1344108, verbose = TRUE, maxiter = 5)

##save the imputed data matrix using filename$ximp 
write.csv(G1344108.Forest$ximp, file = 'G1344108_output.csv')

Question How to loop through the files in a folder?

I run the code in this way:

   all.files <- list.files()
   my.files <- grep(".*csv", all_files, value=T)
            for(i in my.files){
    # do your operations here
    G1344108.Forest <- missForest(G1344108, verbose = TRUE, maxiter = 5)
    # save
    output.filename <- gsub("(.*?).csv", "\\1.csv", i)
    write.table(G1344108.Forest$ximp, output.filename)
}

and it reurns me these following errors:

Error in grep(".*csv", all_files, value = T) : 
  object 'all_files' not found
Error: object 'my.files' not found