i've made some additions to the file to explain the source code

eko.c

@@ -5,7 +5,7 @@
 
 int main( int argc, char **argv)
 {
-// register ne sert plus de nos jours
+// register is a bit useless nowadays
 	register int i, nflg;
 	nflg = 0;
 // Le flag "n" sert à rajouter un saut de ligne

testargs.c

@@ -1,3 +1,6 @@
+// This file displays the GDMSESSION environment variable
+// Try with others if you want, you know how to now
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

wc.pl

@@ -1,5 +1,7 @@
 #!/usr/bin/perl -w
 
+# This script displays the number of lines in a file
+
 use strict;
 
 die "un argument svp ! " if !defined ($ARGV[0]);