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Q&A Line-drawing algorithm prints nonsensical intermediate Y values. Where is the problem?

I answered myself as it can be found here. Silly me! The root of the entire problem was the type used in both point.x and point.y: typedef unsigned int uint; typedef struct { uint x; ...

posted 6d ago by aura-lsprog-86‭  ·  edited 6d ago by aura-lsprog-86‭

Answer
#2: Post edited by user avatar aura-lsprog-86‭ · 2025-02-15T07:40:22Z (6 days ago)
Remove commented unsigned int typedef used in the correction.
  • _I answered myself as it can be found [here](https://stackoverflow.com/a/33534714/5397930)._
  • <hr />
  • Silly me! The root of the entire problem was the type used in both `point.x` and `point.y`:
  • typedef unsigned int uint;
  • typedef struct {
  • uint x;
  • uint y;
  • } point;
  • As both are unsigned integers, they "wrap up" once they receive a negative value, just like in the MCVE. This gets corrected by just changing `uint` to `int`:
  • /* typedef unsigned int uint; */
  • typedef struct {
  • int x;
  • int y;
  • } point;
  • So keep this in mind when using signed and unsigned numbers!
  • _I answered myself as it can be found [here](https://stackoverflow.com/a/33534714/5397930)._
  • <hr />
  • Silly me! The root of the entire problem was the type used in both `point.x` and `point.y`:
  • typedef unsigned int uint;
  • typedef struct {
  • uint x;
  • uint y;
  • } point;
  • As both are unsigned integers, they "wrap up" once they receive a negative value, just like in the MCVE. This gets corrected by just changing `uint` to `int`:
  • typedef struct {
  • int x;
  • int y;
  • } point;
  • So keep this in mind when using signed and unsigned numbers!
#1: Initial revision by user avatar aura-lsprog-86‭ · 2025-02-15T07:38:33Z (6 days ago)
_I answered myself as it can be found [here](https://stackoverflow.com/a/33534714/5397930)._

<hr />

Silly me! The root of the entire problem was the type used in both `point.x` and `point.y`:

    typedef unsigned int uint;

    typedef struct {
        uint x;
        uint y;
    } point;

As both are unsigned integers, they "wrap up" once they receive a negative value, just like in the MCVE. This gets corrected by just changing `uint` to `int`:

    /* typedef unsigned int uint; */

    typedef struct {
        int x;
        int y;
    } point;

So keep this in mind when using signed and unsigned numbers!