Write a C program myls whose behavior resembles that of the system command ls. myls must print the names of files in the current directory in columns of equal width. myls must accept the following parameters:

$ myls [-rs]

-s switch sorts the filenames in the lexicographical order. The file names must be arranged in sequence so that the names in column 1 are followed by the names in column 2, and so on. -r switch sorts the filenames in the reverse lexicographical order. When no switches are present, myls does not need to sort the file names.

Consider using the qsort() library function that implements the quicksort algorithm to sort an array.

$ ls

dirA file2.txt file5.txt file8.txt file0.txt file3.txt file6.txt file9.txt file1.txt file4.txt file7.txt