Complete string matching

Question

I have a vector of strings like for example jk <- c("abc", "lkg", "mno", "ike") and a data frame df that looks like

names nos
 abc    1
 pqe    2
 mno    3

Where first I convert the string in the names column to character strings by using as.character(df$names)

I want to check if the string in column is contained into vector jk So, I wrote a function as below

res <- function(p) {
   if(grep(p, jk, fixed=TRUE) > 0) {
            return(1)
    else {
            return(0)
    }
} 

The desired output should be as follows

names nos res
 abc    1   1
 pqe    2   0
 mno    3   1

But when I perform the following function call

df$res <- lapply(df$names, FUN=res)

I get the following error

Error in if (grep(p, jk, fixed=TRUE) > 0) { : 
  argument is of length zero

when I do the following function call

df$res <- apply(df$names, M FUN=res)

I get the following error.

Error in apply(X = d$names, MARGIN = 1, FUN = res) : 
  dim(X) must have a positive length

How do I get the desired output? Please help!