std::qsort
From cppreference.com
Defined in header
<cstdlib>
|
||
void qsort( void *ptr, std::size_t count, std::size_t size,
int (*comp)(const void *, const void *) ); |
||
Sorts the given array pointed to by ptr
in ascending order. The array contains count
elements of size
bytes. Function pointed to by comp
is used for object comparison.
If comp
indicates two elements as equivalent, their order is undefined.
Contents |
[edit] Parameters
ptr | - | pointer to the array to sort |
count | - | number of element in the array |
size | - | size of each element in the array in bytes |
comp | - | comparison function which returns a negative integer value if the first argument is less than the second, a positive integer value if the first argument is greater than the second and zero if the arguments are equal. int cmp(const void *a, const void *b); The function must not modify the objects passed to it. |
[edit] Return value
(none)
[edit] Notes
The type of the elements of the array must be a trivial type, otherwise the behavior is undefined.
[edit] Example
The following code sorts an array of integers using qsort()
.
Run this code
#include <iostream> #include <cstdlib> int compare_ints(const void* a, const void* b) // comparison function { int arg1 = *reinterpret_cast<const int*>(a); int arg2 = *reinterpret_cast<const int*>(b); if(arg1 < arg2) return -1; if(arg1 > arg2) return 1; return 0; } int main() { int a[] = { -2, 99, 0, -743, 2, 3, 4 }; constexpr std::size_t size = sizeof(a)/sizeof(int); std::qsort(a, size, sizeof(int), compare_ints); for (int ai : a) std::cout << ai << ' '; }
Output:
-743 -2 0 2 3 4 99
[edit] See also
searches an array for an element of unspecified type (function) |
|
sorts a range into ascending order (function template) |
|
(C++11)
|
checks if a type is trivial (class template) |
C documentation for qsort
|