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Notes from Effective STL

📅 2010-May-25 ⬩ ✍️ Ashwin Nanjappa ⬩ 🏷️ cpp, notes, stl ⬩ 📚 Archive

I recently read Effective STL by Scott Meyers. My review of the book can be found here. Below are my notes from the book:

string is typedef basic_string<char>. wstring is typedef basic_string<wchar_t>.

Scott does not mention this, but I find this useful because when you get compilation errors on string, they will mention basic_string<> and not string.

class Foo;
typedef std::vector<Foo> FooVec;
typedef FooVec::iterator FooVecIter;
for (int i = 0; i < MAX; ++i)
    vec.push_back(arr[i]);

Try this:

std::copy( arr, arr, std::back_inserter(vec) );

For an example usage of std::back_inserter see this post.

Use the erase-remove idiom to achieve actual removal:

fooVec.erase( std::remove(), fooVec.end() );
if ( !fooVec.empty() )  // This is important!
    someCFunctionCall( &v[0], v.size() );

It is a pseudo-container with a compressed representation of bools. Avoid using std::vector<bool>, use std::deque<bool> instead. It offers everything that the former does.

STLContainer v;
STLContainer::const_iterator ci = SomeFunction();
STLContainer::iterator i( v.begin() );
std::advance( i, std::distance<STLContainer::const_iterator>( i, ci ));

The base() iterator of a reverse_iterator points 1 element in front of the reverse_iterator position. Use with care.

Useful for unformatted input from files:

// Read file to string
std::ifstream iFile("haha.txt");
std::string fileData( std::istreambuf_iterator<char>( iFile ) ), std::istreambuf_iterator<char>() );

This usually leads to bugs. Instead, whenever possible use one of the inserters: std::inserter, std::back_inserter or std::front_inserter.

For an example usage of std::back_inserter see this post.

Ordered by performance, best to worst:

partition
stable_partition
nth_element
partial_sort
sort
stable_sort

These are:

binary_search
lower_bound
upper_bound
equal_range
set_union
set_intersection
set_difference
set_symmetric_difference
merge
inplace_merge
includes

Predicate is a function that returns bool. Pure function is a function whose return value depends only on its input parameters. It does not have any side effects.

Inherit functors from std::unary_function or std::binary_function so that the necessary types are defined nicely for you.

Defining functors as classes or structs is purely a matter of style. STL uses structs. Some may find it better since there is no need to declare it as public.

Passing functors is actually faster than passing pointer to a function! 😊


© 2022 Ashwin Nanjappa • All writing under CC BY-SA license • 🐘 @codeyarns@hachyderm.io • 📧