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STL Code Snippets
// Vector:
vector vec;
vec.push_back( name ); // push_back() means append
vec.clear();
// Iterating thru a container:
vector files;
vector::iterator itr;
for ( itr = files.begin(); itr != files.end(); ++itr )
cout << *itr << endl;
// Iterating by subscript using an index (N/A to associative containers):
vector vec;
for ( int i = 0; i < vec.size(); ++i )
// Building and iterating thru a map and using pairs:
map mp;
mp.insert( pair( "a", 1 ) );
mp.insert( pair( "b", 2 ) );
mp.insert( pair( "c", 3 ) );
map::iterator itr;
for ( itr = mp.begin(); itr != mp.end(); ++itr )
cout << itr->first << " " << itr->second << endl;
// To test if a key exists in a map/set:
if ( mMap.find(key) != mMap.end() )
// Adding then removing from a container.
list l;
for ( int i = 0; i < 10; ++i )
l.push_back( i ); // append
while ( ! l.empty() )
{ // Prints/pops oldest (head) element first,
cout << l.front() << endl;
l.pop_front();
}
// If no match.
if ( map.find("key") == map.end() ) cout << "not found" << endl;
// Print a container.
list con;
copy( con.begin(), con.end(), ostream_iterator(cout," ") );
// Copy a container:
copy( con1.begin(), con1.end(),
con2 ); // WRONG/PITFALL if con2 smaller than con1
con2.clear();
copy( con1.begin(), con1.end(),
back_inserter(con2) ); // OK if con2 smaller than con1
// Sorting using a binary predicate:
// An alternative (using the container container pointers instead
// of values) that doesn't need a binary predicate is to define
// your own operator<() which sort() uses by default.
bool BinPred( const Class& o1, const Class& o2 )
{
return o1.val < o2.val;
}
vector vec;
sort( vec.begin(), vec.end(), BinPred );
// A function that returns a pair.
// The pair is returned by value (like a struct would be, so it isn't dangling).
std::pair
AddMul( float x, float y )
{
std::pair res;
res.first = x + y;
res.second = x * y;
return res;
}
// Print a binary number in base 2 using bitset.
#include
bitset<8> val = 0xff;
cout << val;
// Turn string to all upper-case.
string s;
transform( s.begin(), s.end(),
s.end(),
toupper );
// Distance between two iterators.
distance( itr1, itr2 )
// Getting the iterator of an item that was inserted into a map:
// (a multimap/multiset differs, adapted from gfx_share.hh)
std::pair insertion;
insertion = mMap.insert( std::make_pair( *obj, std::make_pair(copy,1) ) );
itr = insertion.first; // insertion is assumed to succeed (bool not checked)
// Replacing/substituting chars of a string.
// string::replace() is really an overwrite, not a substitution.
char
Unix2DosDirChar( char c )
{
return c == '/' ? '\': c;
}
string
Unix2DosDir( const string& dirname )
{
string s = dirname;
std::transform( s.begin(), s.end(),
s.begin(),
Unix2DosDirChar );
return s;
}
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