NAME¶

std::set::value_comp - std::set::value_comp

Synopsis¶

std::set::value_compare value_comp() const;

Returns the function object that compares the values. It is the same as key_comp.

Parameters¶

(none)

Return value¶

The value comparison function object.

Complexity¶

Constant.

Example¶

// Run this code

#include <cassert>
#include <iostream>
#include <set>

// Example module 97 key compare function
struct ModCmp {
bool operator()(const int lhs, const int rhs) const
{
return (lhs % 97) < (rhs % 97);
}
};

int main()
{
std::set<int, ModCmp> cont{1, 2, 3, 4, 5};

// Same behaviour as key_comp()
auto comp_func = cont.value_comp();

const int val = 100;

for (int key : cont) {
bool before = comp_func(key, val);
bool after = comp_func(val, key);
if (!before && !after)
std::cout << key << " equivalent to key " << val << '\n';
else if (before)
std::cout << key << " goes before key " << val << '\n';
else if (after)
std::cout << key << " goes after key " << val << '\n';
else
assert(0); // Cannot happen
}
}

Output:¶

1 goes before key 100
2 goes before key 100
3 equivalent to key 100
4 goes after key 100
5 goes after key 100

See also¶

key_comp returns the function that compares keys
(public member function)