语法：

#include <algorithm>
 
template <class RandomAccessIterator>
void sort( RandomAccessIterator start, RandomAccessIterator end );
 
template <class RandomAccessIterator, class Compare>
void sort( RandomAccessIterator start, RandomAccessIterator end, Compare cmp );

排序 sort 算法将[start,end)范围内的元素排列成升序。如果两个元素相同，不能保证它们的顺序。

如果函数对象cmp被给定，那么它将取代<用来比较两个对象。cmp应该产生从start到end严格的弱顺序。

注意sort只对RandomAccessIterators操作。比如，你不能对list使用sort；而应该使用list::sort。

start and end are RandomAccessIterators pointing to the range of elements to be sorted.

cmp is an optional function object that is used in place of < to perform comparisons between pairs of elements.

none

下面的代码将一组整数向量排列成升序：

std::vector<int> v;
v.push_back( 23 );
v.push_back( -1 );
v.push_back( 9999 );
v.push_back( 0 );
v.push_back( 4 );
 
std::cout << "Before sorting: ";
for( unsigned int i = 0; i < v.size(); i++ ) {
  std::cout << v[i] << " ";
}
std::cout << std::endl;
 
std::sort( v.begin(), v.end() );
 
std::cout << "After sorting: ";
for( unsigned int i = 0; i < v.size(); i++ ) {
  std::cout << v[i] << " ";
}
std::cout << std::endl;

When run, the above code displays this output:

Before sorting: 23 -1 9999 0 4
After sorting: -1 0 4 23 9999

Alternatively, the following code uses the sort function to sort a normal array of integers, and displays the same output as the previous example:

const unsigned int array_size = 5;
int array[array_size] = { 23, -1, 9999, 0, 4 };
 
std::cout << "Before sorting: ";
for( unsigned int i = 0; i < array_size; i++ ) {
  std::cout << array[i] << " ";
}
std::cout << endl;
 
std::sort( array, array + array_size );
 
std::cout << "After sorting: ";
for( unsigned int i = 0; i < array_size; i++ ) {
  std::cout << array[i] << " ";
}
std::cout << std::endl;

This next example shows how to use sort with a user-specified comparison function. The function cmp is defined to do the opposite of the < operator. When sort is called with cmp used as the comparison function, the result is a list sorted in descending, rather than ascending, order:

bool cmp( int a, int b ) {
  return a > b;
}
 
...
 
std::vector<int> v;
for( int i = 0; i < 10; i++ ) {
  v.push_back(i);
}
 
std::cout << "Before: ";
for( int i = 0; i < 10; i++ ) {
  std::cout << v[i] << " ";
}
std::cout << endl;
 
std::sort( v.begin(), v.end(), cmp );
 
std::cout << "After: ";
for( int i = 0; i < 10; i++ ) {
  std::cout << v[i] << " ";
}
std::cout << std::endl;

The algorithm behind sort is the introsort algorithm. sort runs in O(N log(N)) time (average and worst case) which is faster than polynomial time but slower than linear time.

binary_search, merge, partial_sort, partial_sort_copy, stable_sort, qsort