find_if() Function in C++

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This C++ program demonstrates the find_if algorithm on string vector. The find_if takes three arguments – of which the first two are iterators to the beginning and end of the container and the third argument is predicate. The predicate we are passing returns true on strings starting with ‘P’.

Here is the source code of the C++ program demonstrates the find_if algorithm on string vector. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

  1. /*
  2.  * C++ Program to demonstrate find_if() on string vector
  3.  */
  4. #include <iostream>
  5. #include <algorithm>
  6. #include <string>
  7. #include <vector>
  8.  
  9. bool fun(std::string s)
  10. {
  11.     if(s[0] == 'P')
  12.         return true;
  13.     else 
  14.         return false;
  15. }
  16.  
  17. int main()  
  18. {
  19.     std::vector <std::string>::iterator i;
  20.     std::vector <std::string> v;
  21.     v.push_back("Apple");
  22.     v.push_back("Apricot");
  23.     v.push_back("Kiwi");
  24.     v.push_back("Orange");
  25.     v.push_back("Peach");
  26.     v.push_back("Pineapple");
  27.  
  28.     i = find_if(v.begin(), v.end(), fun);
  29.     if (i != v.end())
  30.     {
  31.         std::cout << "String at position " << (i - v.begin() + 1)
  32.                   << " starts with P" << std::endl;
  33.         std::cout << "The string is : \"" << *i
  34.                   << "\"" << std::endl;
  35.     }
  36.     return 0;
  37. }

$ a.out
String at position 5 starts with P
The string is : "Peach"

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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