(C++) std::binary_search

 

std::binary_search is an STL algorithm to determine if a value is present in a sorted container.

 

 

 

 

 

Project and source code

 

Operating system: Ubuntu 10.04 LTS Lucid Lynx

IDE: Qt Creator 2.0.0

Project type: Qt4 console Application

Compiler: G++ 4.4.1

Libraries used:

• STL: from GCC, shipped with Qt Creator 2.0.0

 

• Download the Qt Creator project 'CppBinary_search' (zip)

 

 

 

 

 

main.cpp

 

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#include <algorithm> #include <cassert> #include <iostream> #include <vector> struct Gossip {   Gossip(const int any_i) : i(any_i) {}   private:   int i;   friend bool operator<(const Gossip& lhs, const Gossip& rhs); }; bool operator<(const Gossip& lhs, const Gossip& rhs) {   std::cout << "bool operator<(const Gossip& lhs, const Gossip& rhs)\n";   return lhs.i < rhs.i; } int main() {   std::vector<Gossip> v;   for (int i=0; i!=100; ++i)   {     v.push_back(Gossip(i));   }   std::cout << "I will be found\n";   assert(std::binary_search(v.begin(),v.end(),Gossip(90))==true);   std::cout << "I will not be found\n";   assert(std::binary_search(v.begin(),v.end(),Gossip(100))==false); }

 

Screen output:

 

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I will be found bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) I will not be found bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs) bool operator<(const Gossip& lhs, const Gossip& rhs)