Code

var fh1 as int
var fh2 as int
var fh3 as int
var fh_out as int
var done as int
var str1 as string
var str2 as string
var str3 as string
var str_out as string

	fh1 = fileOpen("book1.txt")
	fh2 = fileOpen("book2.txt")
	fh3 = fileOpen("book3.txt")

	fh_out = fileOpen("OutFile.txt")
	fileSeek(fh1, 0)
	fileSeek(fh2, 0)
	fileSeek(fh3, 0)
	fileSeek(fh_out, 0)

	done = 0
	While(done = 0)
	{
		If FilePos(fh1) <> FileSize(fh1) Then
		{
			fileReadln(fh1, str1)
		}
		Else
		{
			str1 = ""
		}
		If FilePos(fh2) <> FileSize(fh2) Then
		{
			fileReadln(fh2, str2)
		}
		Else
		{
			str2 = ""
		}
		If FilePos(fh3) <> FileSize(fh3) Then
		{
			fileReadln(fh3, str3)
		}
		Else
		{
			str3 = ""
		}

		If((@Len(str1) > 0) and (@Len(str2) > 0) and (@Len(str3) > 0))
		{
			str_out = str1 + ", " + str2 + ", " + str3
			fileWriteln(fh_out, str_out)
		}
		Else
		{
			done = 1
		}
	}
	fileClose(fh_out)
	fileClose(fh3)
	fileClose(fh2)
	fileClose(fh1)