C++ In a Nutshell

Name

qsort function — Sorts an array

Synopsis

extern "C"
  void qsort(void* base, size_t count, size_t size, int 
            (*compare)(const void*, const void*))
extern "C++"
  void qsort(void* base, size_t count, size_t size, int 
            (*compare)(const void*, const void*))

The qsort function sorts in ascending order an array of count elements, each of size size bytes, in which base is the pointer to the first element. The array must have POD type. The sort is not stable, that is, the relative order of identical elements is not necessarily preserved.

The compare function takes two pointers into the array and compares the elements. It returns an integer: negative if the first element is less than the second, positive if the first is greater than the second, or 0 if the two elements are equal.

The name qsort derives from the original implementation, which used the Quick Sort algorithm. The current standard does not specify which sort algorithm is used, nor does it specify any performance characteristics of the sort algorithm.

Two versions of qsort are declared so the compare function can have "C" linkage or "C++" linkage.

See Also

bsearch function, sort in <algorithm>