C++ Snippets

gistfile1.cpp

/*
Short list of macros and templates from
http://community.topcoder.com/tc?module=Static&d1=tutorials&d2=standardTemplateLibrary
*/
typedef vector<int> vi; 
typedef vector<vi> vvi; 
typedef pair<int,int> ii; 
#define sz(a) int((a).size()) 
#define pb push_back 
#defile all(c) (c).begin(),(c).end() 
#define tr(c,i) for(typeof((c).begin() i = (c).begin(); i != (c).end(); i++) 
#define present(c,x) ((c).find(x) != (c).end()) 
#define cpresent(c,x) (find(all(c),x) != (c).end()) 

/*
Macro to set the beggining and end of a container.
*/

#define all(c) c.begin(), c.end()
vector<int> v1 (100,0);
vector<int> v2 (all(v1));
set<int> s (all(v1)); // Removes duplicates from v1
/*
Macro to traverse a container using iterators
*/

#define tr(container, it) for(auto it = container.begin(); it != container.end(); it++)

tr (container, it)
{
    cout << (*it) << endl;
}

/*
Macros to find elements in set/maps or vectors
*/
// For sets and maps
#define present(container, element) (container.find(element) != container.end()) 

// For vectors
#define cpresent(container, element) (find(all(container),element) != container.end())

/* 
Passing an iterator instead of a container.
This solution works even for arrays []
 */

template <class Iter>
double product( Iter start, Iter stop )
{
  double prod = 1;

  while ( start != stop ) prod *= *start++;

  return prod;

}

Examples:
double nums[] = { 1.2, 3.0, 3.5, 2.8 };
return product( nums, nums + 4 );

std::vector<int> v = { 1.2, 3.0, 3.5, 2.8 };
return product (v.begin(), v.end());

/*
Tokenize a string 'in' with a delimiter 'kar'.
*/

vector< string > tokenize( string in, string kar ) { 
    string::iterator cp = in.begin(); 
    vector< string > oot; 
    while( cp != in.end() ) { 
        while( cp != in.end() && count( kar.begin(), kar.end(), *cp ) ) 
            cp++; 
        if( cp != in.end() ) 
            oot.push_back( string( cp, find_first_of( cp, in.end(), kar.begin(), kar.end() ) ) ); 
        cp = find_first_of( cp, in.end(), kar.begin(), kar.end() ); 
    }; 
    return oot; 
};

/*
Another tokenize method working on a 
string 'in' with delimiters inside 'token'.
*/
#include <iostream>
#include <cstring>
#include <string>
#include <vector>

std::vector<std::string> tokenize_v2 (std::string in, const char * token)
{
    char * cstr = new char [in.length()+1];
    std::strcpy (cstr, in.c_str());
    std::vector<std::string> parsed_str;

// cstr now contains a c-string copy of in

    char * p = std::strtok (cstr, token);
    while (p!=0)
    {
        parsed_str.push_back(p);
        // std::cout << p << '\n';
        p = std::strtok(NULL, token);
    }

    delete[] cstr;
    return parsed_str;
}

int main(int argc, char const *argv[])
{
    std::string sentence = "I,am,a,string with blank spaces and commas";
    std::vector<std::string> splitted;
    const char * delimiters = " ,.-";
    splitted = tokenize_v2(sentence, delimiters);
    for (std::string x : splitted)
        std::cout << x << '\n';
    return 0;
}