< cpp‎ | algorithm
Revision as of 07:19, 13 June 2013 by Nate (Talk | contribs)

Algorithm library
Execution policies (C++17)
Non-modifying sequence operations
Modifying sequence operations
Operations on uninitialized storage
Partitioning operations
Sorting operations
Binary search operations
Set operations (on sorted ranges)
Heap operations
Minimum/maximum operations

Numeric operations
C library
Defined in header <algorithm>
template< class T >
const T& min( const T& a, const T& b );
template< class T, class Compare >
const T& min( const T& a, const T& b, Compare comp );
template< class T >
T min( std::initializer_list<T> ilist);
(3) (since C++11)
template< class T, class Compare >
T min( std::initializer_list<T> ilist, Compare comp );
(4) (since C++11)

1-2) Returns the smaller of the two values.

3-4) Returns the smallest of the values in initializer list ilist.

The (1,3) versions use operator< to compare the values, the (2,4) versions use the given comparison function comp.



a, b - the values to compare
ilist - initializer list with the values to compare
cmp - comparison function object (i.e. an object that satisfies the requirements of Compare) which returns ​true if if a is less than b.

The signature of the comparison function should be equivalent to the following:

 bool cmp(const Type1 &a, const Type2 &b);

The signature does not need to have const &, but the function object must not modify the objects passed to it.
The types Type1 and Type2 must be such that an object of type T can be implicitly converted to both of them. ​

Type requirements
T must meet the requirements of LessThanComparable. for the overloads (1) and (3)
T must meet the requirements of CopyConstructible. for the overloads (3) and (4)

Return value

1-2) The smaller of a and b. If the values are equivalent, returns a.

3-4) The smallest value in ilist. If several values are equivalent to the smallest, returns the leftmost such value.


1-2) Constant

3-4) Linear in ilist.size()

Possible implementation

First version
template<class T> 
const T& min(const T& a, const T& b)
    return (b < a) ? b : a;
Second version
template<class T, class Compare> 
const T& min(const T& a, const T& b, Compare comp)
    return (comp(b, a)) ? b : a;
Third version
template<class T>
T min( std::initializer_list<T> ilist)
    return *std::min_element(ilist.begin(), ilist.end());
Fourth version
template<class T, class Compare>
T min(std::initializer_list<T> ilist, Compare comp)
    return *std::min_element(ilist.begin(), ilist.end(), comp);


#include <algorithm>
#include <iostream>
#include <string>
int main()
    std::cout << "smaller of 1 and 9999: " << std::min(1, 9999) << '\n'
              << "smaller of 'a', and 'b': " << std::min('a', 'b') << '\n'
              << "shortest of \"foo\", \"bar\", and \"hello\": " <<
                  std::min( { "foo", "bar", "hello" },
                            [](const std::string& s1, const std::string& s2) {
                                 return s1.size() < s2.size();
                             }) << '\n';


smaller of 1 and 9999: 1
smaller of 'a', and 'b': a
shortest of "foo", "bar", and "hello": foo

See also

returns the greater of the given values
(function template) [edit]
returns the smaller and larger of two elements
(function template) [edit]
returns the smallest element in a range
(function template) [edit]