Complete REXX course, from 0, for Windows and z/OS

Install the Open Object Rex interpreter and a text editor, set up a RECs folder, configure editor line numbering, then create and run a Hello Rex program with post command.

Learn how to show and hide file extensions in Windows, toggle the 'hide extensions for known file types' option, and understand how changing an extension can affect file usability.

Explore the Rexx parse instruction, including pass options to split a string into words or columns, assign to variables, use separators, and build a final variable with pass value.

Explore how to implement simple do loops in REXX, group instructions with do, validate user input, and use a start label, a counter, and empty-input messages.

Explore the iterate instruction in Rexx programming to control loops by returning to the loop start, skipping remaining instructions, and deciding when to continue, exit, or loop again.

Explore do while and do until loops in Rexx, showing how do while tests expressions before each entry and how do until executes at least once, prompting for a password.

Discover the three comment styles in REXX code, including single-line, multi-line, and title comments, and learn how to place literals using double or single quotes, with examples.

Explore how Rex uses variables, literals, and concatenation, including quotes and spacing rules; apply colon, semicolon, and comma to labels, sentences, and line continuation, with built-in functions.

Explore REXX arithmetic, comparison, and logical operators, including +, -, *, /, and %, with integer division and remainders, exponentiation (**), and/or/xor logic for conditionals.

Learn how Rex builds internal functions, passes literals or variables as parameters, and uses string, word, justification, numeric, environment, and I/O functions to manipulate data and interact with the system.

Explore copies to repeat strings, dlstr to delete characters, and insert to place a new string with parameters like position, length, and padding or bound symbols.

Explore rex overlay, reverse, and substring to manipulate strings: overlay inserts a new string into the original at a start position with optional length and path; reverse flips, substring extracts.

Master REXX string handling by using length to count characters, post to locate the first occurrence, and lastpos to search from the end, including spaces and symbols.

Learn arg handling with arc to count and access parameters, validate data types with datatype, and build character ranges with xrange for efficient string manipulation.

Center centers a string in width l, padding with spaces or a chosen character and truncating if needed; strip removes leading or trailing characters per option RB, L, or D.

Explore the left and right functions in rex, which take an L parameter and a string, returning a fixed number of characters with padding (spaces or a pad) and truncation.

Explore the abs function to obtain an absolute value, the distance from zero, and use max and min to find the largest or smallest numbers, including nested calls.

Describe the sign function: returns 1 for positive, -1 for negative, and 0 for zero. Use the random function to generate numbers in a range, 0-999 or 10-200 for games.

Learn to use linein, lineout, and lines to read, write, and count lines in a file, control the reading location, and manage line records across Windows and Linux.

Learn to read and write an entire file in Rexx by using programs that copy records from an input file to an output file, with line in, counters, and loops.