std::qsort
From Cppreference
| Defined in header <cstdlib>
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| void qsort( const void *ptr, size_t count, size_t size,
int (*comp)(const void *, const void *) ); |
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Sorts the given array pointed to by ptr in ascending order. The array contains count elements of size size. Function pointed to by comp is used for object comparison.
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[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.
The function must not modify the objects passed to it. |
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[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().
#include <iostream> #include <cstdlib> int compare_ints(const void* a, const void* b) // comparison function { int* arg1 = (int*) a; int* arg2 = (int*) b; if( *arg1 < *arg2 ) return -1; else if( *arg1 == *arg2 ) return 0; else return 1; } int main() { int a[] = { -2, 99, 0, -743, 2, 3, 4 }; int size = 7; std::qsort(a, size, sizeof(int), compare_ints); for (int i = 0; i < size; i++) { std::cout << a[i] << " "; } std::cout << '\n'; }
Output:
-743 -2 0 2 3 4 99
[edit] See also
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searches an array for an element of unspecified type (function) |
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sorts a range into ascending order (function template) |
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checks if a type is trivial (class template) |
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