Compare Functions
The compare.h header file contains a collection of compare functions for various primitive types.
They come in two flavors:
Examples
In the following example we use cx_cmp_int32 as the compare function for a CxList of int32_t values.
CxList *list = cxArrayListCreate(
cxDefaultAllocator, // use the default allocator
sizeof(int32_t), // the size of one element
256 // reseve space for 256 elements
);
// set the compare function for the elements
cxSetCompareFunc(list, cx_cmp_int32);
In the next example we simply want to compare two double values with rounding tolerance. Note how the use of the cx_vcmp flavor makes it unnecessary to store the literal in a variable just to be able to take an address.
double x = ...
if (0 == cx_vcmp(x, 47.11)) {
// do something when equal (except tolerance)
}
If you only have a cx_compare_func at hand but need to call a function that expects a cx_compare_func2 and a context, you can use cx_cmp_wrap and the cx_compare_func_wrapper struct to wrap your function.
void some_fun(int x, int y, cx_compare_func2 f, void *context);
cx_compare_func_wrapper wrapper = {my_cmp_fun};
some_fun(x, y, cx_cmp_wrap, &wrapper);
List of Functions
#include <cx/compare.h>
// Value Flavour
int cx_vcmp_double(double a, double b);
int cx_vcmp_float(float a, float b);
int cx_vcmp_int(int a, int b);
int cx_vcmp_int16(int16_t a, int16_t b);
int cx_vcmp_int32(int32_t a, int32_t b));
int cx_vcmp_int64(int64_t a, int64_t b);
int cx_vcmp_intptr(intptr_t a, intptr_t b);
int cx_vcmp_longint(long int a, long int b);
int cx_vcmp_longlong(long long a, long long b);
int cx_vcmp_uint(unsigned int a, unsigned int b);
int cx_vcmp_uint16(uint16_t a, uint16_t b);
int cx_vcmp_uint32(uint32_t a, uint32_t b);
int cx_vcmp_uint64(uint64_t a, uint64_t b);
int cx_vcmp_size(size_t a, size_t b);
int cx_vcmp_uintptr(uintptr_t a, uintptr_t b);
int cx_vcmp_ulongint(unsigned long int a, unsigned long int b);
int cx_vcmp_ulonglong(unsigned long long a, unsigned long long b);
// Pointer Flavour
// (unspecified types make them compatible with cx_compare_func)
int cx_cmp_ptr(const void *a, const void *b);
int cx_cmp_double(const void *a, const void *b);
int cx_cmp_float(const void *a, const void *b);
int cx_cmp_int(const void *a, const void *b);
int cx_cmp_int16(const void *a, const void *b);
int cx_cmp_int32(const void *a, const void *b);
int cx_cmp_int64(const void *a, const void *b);
int cx_cmp_intptr(const void *a, const void *b);
int cx_cmp_longint(const void *a, const void *b);
int cx_cmp_longlong(const void *a, const void *b);
int cx_cmp_uint(const void *a, const void *b);
int cx_cmp_uint16(const void *a, const void *b);
int cx_cmp_uint32(const void *a, const void *b);
int cx_cmp_uint64(const void *a, const void *b);
int cx_cmp_size(const void *a, const void *b);
int cx_cmp_uintptr(const void *a, const void *b);
int cx_cmp_ulongint(const void *a, const void *b);
int cx_cmp_ulonglong(const void *a, const void *b);
Comparing with Context
Sometimes it might be necessary to have some context available during the comparison. For this purpose, the cx_compare_func2 specifies a signature with an additional void* argument. The Collections API supports those functions via the cxSetAdvancedCompareFunc() macro.
On the other hand, some API might provide only the variant with three arguments, but you want to use one of the compare functions defined above. In this case, they can easily be wrapped
#include <cx/compare.h>
typedef struct {
cx_compare_func cmp;
} cx_compare_func_wrapper;
// signature is cx_compare_func2 compatible
int cx_cmp_wrap(const void *a, const void *b, void *wrapper);
// example: imagine there is some_sort_fun()
// that only supports 3-argument compare functions
cx_compare_func_wrapper wrapper = {cx_cmp_int};
some_sort_fun(array, cx_cmp_wrap, &wrapper);
31 December 2025