C++ Renaissance

Modern C++ software development

C++11 new features

leave a comment »

Lambda expressions

Definition: Anonymous functions:

[capture](parameters)->return_type {body}

The parameter capture is defined as following:

[] //no variables defined. Using one will result in error
[x, &y] //x is captured by value, y is captured by reference
[&] //any external variable is implicitly captured by reference if used
[=] //any external variable is implicitly captured by value if used
[&, x] //x is explicitly captured by value. Other variables will be captured by reference
[=, &z] //z is explicitly captured by reference. Other variables will be captured by value

Example:

   char s[]="Hello World!";
   int Uppercase = 0; //modified by the lambda
   for_each(s, s+sizeof(s),
              [&Uppercase] (char c) { if (isupper(c)) Uppercase++;  });
   cout<< Uppercase<<" uppercase letters in: "<< s<<endl;

Automatic type deduction: auto

auto x=0; //x has type int because 0 is int
auto c='a'; //char
auto d=0.5; //double
auto national_debt=14400000000000LL;//long long

Object or expression type: decltype

const vector<int> vi;
typedef decltype (vi.begin()) CIT;
CIT another_const_iterator;

Initialization

vector vs<string>={ "first", "second", "third"};
map singers = { {"Lady Gaga", "+1 (212) 555-7890"}, 
                {"Beyonce Knowles", "+1 (212) 555-0987"}};
 class C { 
        int a=7; //Initialization in the header
 public: C(); };

References: [1][2]

Advertisements

Written by javiersigler

June 18, 2011 at 4:53 pm

Posted in C++11, Uncategorized