# <stdlib.h>

**[<stdlib.h>](https://en.cppreference.com/w/c/header/stdlib)** covers memory allocation (`malloc`, `calloc`, `free`), type conversion (`atoi`, `strtol`), sorting/searching (`qsort`, `bsearch`), and process control (`exit`, `abort`). It's the "junk drawer" of the C standard library.

Always check `malloc` for NULL; always check `qsort` comparators carefully for overflow.

## Example

This example sorts integers with qsort and binary-searches the result.

```c
// compile: gcc -o stdlibexample stdlibexample.c
// run: ./stdlibexample
// description: sort array with qsort, then search it with bsearch

#include <stdlib.h>
#include <stdio.h>

int cmp_int(const void* a, const void* b) {
    return *(int*)a - *(int*)b;
}

int main() {
    int arr[] = {5, 2, 8, 1, 9, 3};
    int n = sizeof(arr) / sizeof(arr[0]);
    
    qsort(arr, n, sizeof(int), cmp_int);
    
    printf("sorted: ");
    for (int i = 0; i < n; i++) printf("%d ", arr[i]);
    printf("\n");
    
    int key = 8;
    int* found = bsearch(&key, arr, n, sizeof(int), cmp_int);
    printf("search for 8: %s\n", found ? "found" : "not found");
    
    return 0;
}
```