std::search example on vector and string

Continuing from last weeks theme, here is a simple example of std::search.

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
#include <iostream>
#include <vector>
#include <string>
#include <algorithm> //needed for std::search

using namespace std;

bool isOdd(int i) 
{
  return ((i%2)==1);
}

int main()
{
  vector<int> v1;
  v1.push_back(88);
  v1.push_back(99);
  v1.push_back(22);
  v1.push_back(33);
  v1.push_back(44);
  v1.push_back(55);
  v1.push_back(66);
  v1.push_back(77);

  //Demonstrating Search - Matching Case
  vector<int> v2;
  v2.push_back(22);
  v2.push_back(33);
  v2.push_back(44);

  vector<int>::const_iterator it = search(v1.begin(), v1.end(), v2.begin(), v2.end());
  if(it != v1.end())
  {
    cout<<"Found: "<<*it<<endl;
    cout<<"Position = "<<it - v1.begin() + 1<<endl;
  }
  else
  {
    cout<<"Not Found"<<endl;
    cout<<"Position = -1"<<endl;
  }

  //Demonstrating Search - Non-Matching Case
  vector<int> v3;
  v3.push_back(22);
  v3.push_back(33);
  v3.push_back(444); //non matching

  it = search(v1.begin(), v1.end(), v3.begin(), v3.end());
  if(it != v1.end())
  {
    cout<<"Found: "<<*it<<endl;
    cout<<"Position = "<<it - v1.begin() + 1<<endl;
  }
  else
  {
    cout<<"Not Found"<<endl;
    cout<<"Position = -1"<<endl;
  }

  //Use the search to find strings
  string s1="Hello, this is Zahid";

  //Matching case
  string s2="Zahid";

  string::const_iterator it2 = search(s1.begin(), s1.end(), s2.begin(), s2.end());
  if(it2 != s1.end())
  {
    cout<<"Found: "<<*it2<<endl;
    cout<<"Position = "<<it2 - s1.begin() + 1<<endl;
  }
  else
  {
    cout<<"Not Found"<<endl;
    cout<<"Position = -1"<<endl;
  }

  //Non-Matching case
  string s3="None";

  it2 = search(s1.begin(), s1.end(), s3.begin(), s3.end());
  if(it2 != s1.end())
  {
    cout<<"Found: "<<*it2<<endl;
    cout<<"Position = "<<it2 - s1.begin() + 1<<endl;
  }
  else
  {
    cout<<"Not Found"<<endl;
    cout<<"Position = -1"<<endl;
  }

  return 0;
}

The output is as follows:

std::find and std::find_if for finding information in vectors

Here is a simple program that demonstrates how to use find and find_if with vectors.

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
#include <iostream>
#include <vector>
#include <algorithm> //needed for std::find

using namespace std;

bool isOdd(int i) 
{
  return ((i%2)==1);
}

int main()
{
  vector<int> v1;
  v1.push_back(88);
  v1.push_back(99);
  v1.push_back(22);
  v1.push_back(33);
  v1.push_back(44);
  v1.push_back(55);
  v1.push_back(66);
  v1.push_back(77);

  //Demonstrating Find - Find number 55 and its position, if present
  vector<int>::const_iterator it = find(v1.begin(), v1.end(), 55);
  if(it != v1.end())
  {
    cout<<"Found: "<<*it<<endl;
    cout<<"Position = "<<it - v1.begin() + 1<<endl;
  }
  else
  {
    cout<<"Not Found"<<endl;
    cout<<"Position = -1"<<endl;
  }

  //Demonstrating Find IF - Find the first Odd number and its position
  it = find_if(v1.begin(), v1.end(), isOdd);
  if(it != v1.end())
  {
    cout<<"Found: "<<*it<<endl;
    cout<<"Position = "<<it - v1.begin() + 1<<endl;
  }
  else
  {
    cout<<"No Odd Numbers Found"<<endl;
    cout<<"Position = -1"<<endl;
  }

  return 0;
}

The output is as follows:

Interesting Challenging problem on Code Complexity

Picked up this interesting problem from the following book:



How many execution paths can this simple three line code take:

String EvaluateSalaryAndReturnName( Employee e )
{
  if( e.Title() == "CEO" || e.Salary() > 100000 )
  {
    cout << e.First() << " " << e.Last() << " is overpaid" << endl;
  }
  return e.First() + " " + e.Last();
}

The answer may surprise you. I have embedded the actual pages from Google books. Luckily the whole problem and solution is given. See Item 18.

The size_t confusion

Apparently there could be a lot of confusion with regards to size_t. In 'C' the size_t was defined as an unsigned integer. 'C++' defines it as unsigned integer as well but it has a namespace of std around it. Some compilers may want #include<cstdlib> to use std::size_t.

In any case, it can cause quite some confusion among programmers as to why it is used and what is the size of it. Instead we can #define a type, give it a meaningful name and use it accordingly. Here is my simple example:

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
#include<iostream>
#include<cstdlib> //Used for std::size_t ... on some compilers

#define u16 unsigned short
#define u32 unsigned //integer is implicit

int main()
{
  size_t size = sizeof(size_t);
  std::cout << "Size of size_t is " << size << std::endl;

  std::size_t size2 = sizeof(std::size_t);
  std::cout << "Size of std::size_t is " << size2 << std::endl;

  size_t size3 = sizeof(u16);
  std::cout << "Size of u16 is " << size3 << std::endl;

  size_t size4 = sizeof(u32);
  std::cout << "Size of u32 is " << size4 << std::endl;

  return 0;
}

The output is as follows: