In my first attempt at an editor, written in an amazingly ugly (Borland) C/C++ mix, I assumed text was always delimited with some form of newline. I loaded the

In my first attempt at an editor, written in an amazingly ugly (Borland) C/C++ mix, I assumed text was always delimited with some form of newline. I loaded the initial file into memory completely, and then constructed a "line" array structs, which contained a pointer to the start of the line, a length and a pointer to the 'previous' version. If this was NULL, it was the initially loaded buffer. The editing of a line itself was far from optimal but straight-forward: it involved allocating a new struct, filling it in, when the undo mechanism was enabled pointing the previous version to the currently active version, otherwise pointing to the previous version of the last version (which should be the initial buffer), swapping the line pointer in the line array, and free'ing that old buffer/struct. Inserting a new line involved a memmove of the "line" array and an insert, and worst case a realloc of that array if it was too small. I never really finished it, but I had a primitive undo mechanism in place that had issues with line inserts, which I never ironed out (project was abandoned at that point). It wasn't very memory-friendly when I enabled this undo mechanism, since this caused the entire history of every line being kept indefinitely, and every single-character insert or delete did a full copy of that line - and caused memory issues creating even relatively small files, certainly when starting from scratch, the memory bloat was incredible ^^ Still it was a fun project for me as a 16-year old kid.