SDL_qsort_r(3)

💅 SDL_qsort_r(3) — SDL3 FUNCTIONS ✨

okay bestie, sit down, hydrate, because we're sorting arrays and we're doing it with style. this is a page from the SDL3 FUNCTIONS collection, and today's main character is SDL_qsort_r — the sort that lets you slide a lil userdata pointer into your compare function like a note passed in class. 🫶

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✨ NAME ✨

SDL_qsort_r — Sort an array, passing a userdata pointer to the compare function.

like, you sort stuff. but your compare function also gets a userdata pointer. that's the whole vibe. no cap. 💖

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🎀 SYNOPSIS 🎀

#include <SDL3/SDL_stdinc.h>

void SDL_qsort_r(void *base, size_t nmemb, size_t size, SDL_CompareCallback_r compare, void *userdata);

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🦋 DESCRIPTION 🦋

okay so here's a whole example, and honestly? it eats. 🍓

       typedef enum {
           sort_increasing,
           sort_decreasing,
       } sort_method;

       typedef struct {
           int key;
           const char *string;
       } data;

       int SDLCALL compare(const void *userdata, const void *a, const void *b)
       {
           sort_method method = (sort_method)(uintptr_t)userdata;
           const data *A = (const data *)a;
           const data *B = (const data *)b;

           if (A->key < B->key) {
               return (method == sort_increasing) ? -1 : 1;
           } else if (B->key < A->key) {
               return (method == sort_increasing) ? 1 : -1;
           } else {
               return 0;
           }
       }

       data values[] = {
           { 3, "third" }, { 1, "first" }, { 2, "second" }
       };

       SDL_qsort_r(values, SDL_arraysize(values), sizeof(values[0]), compare, (const void *)(uintptr_t)sort_increasing);

see how the userdata gets smuggled into compare and turned back into a sort_method? that's the entire point, bestie. you want increasing? decreasing? your compare function decides, and userdata tells it which way to go. iconic behavior, honestly. 🌈

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💖 FUNCTION PARAMETERS 💖

• base — a pointer to the start of the array. the beginning. the origin story. ✨
• nmemb — the number of elements in the array. how many little guys we're sorting. 🔢
• size — the size of the elements in the array. each one's lil footprint. 👟
• compare — a function used to compare elements in the array. it does the judging (lovingly). 💅
• userdata — a pointer to pass to the compare function. your secret lil message. 🤫

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🌸 THREAD SAFETY 🌸

It is safe to call this function from any thread. 🧚

go off, thread queen. every thread can sort. no gatekeeping here. 💚

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⭐ AVAILABILITY ⭐

This function is available since SDL 3.2.0. so if you're on something older… bestie, it's giving ✨upgrade✨. 😭

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👑 SEE ALSO 👑

• SDL_bsearch_r(3)
• SDL_qsort(3)

the whole friend group, fr fr. 🫶

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and that's the page!! this manual page came to you courtesy of Simple Directmedia Layer, straight from SDL 3.4.18. go sort something beautiful, bestie. 🎀💖✨