如何在C ++中编译具有大量数据的向量？

Question

I am writting a C++ program which checks if some words exist in Catalan, so I have a vector with the Catalan dictionary:

const vector<string> dict={"aaron","ababol","abac","abaca","abacallanada","abacallanava","abacas","abacial", ... ,"zum-zum","zur","zuric","zwitterio"};

The problem is that the dictionary has 107776 entries, so when I attempt to compile the file:

g++ -Wall file.cc -std=c++0x -o file.exe

it does nothing during a while and then Windows says that it isn't responding and closes it.

How can I compile it? Is there a better way of storing this type of data (arrays, ...)?

Answer 1

You may well have more luck with old-school built-in arrays:

char const * const dict[] = {"aaron",...};

This will generate a load of string literals and an array of pointers to them, which shouldn't be too much of a strain for the compiler. This will also use no more memory than necessary, with little or no work at runtime.

Alternatively, std::array<char const *> should be just as efficient, with more of a C++ look and feel.

Your version also has to generate an enormous amount of code to build an initializer_list from those, construct a string from each, and add each string to the vector. It will also require more than twice as much memory as each string literal needs to be copied into memory allocated at runtime, and then all those pointers need to be stored in another run-time allocated array.

The disadvantage is that you may end up constructing a temporary string each time you read from the dictionary. If that's a concern, then an array of std::string might be a reasonable compromise.

Answer 2

Store it in external file, and load on demand. This is the best solution, otherwise I suppose you should split your vector into multiple vectors and maybe put them into separate cpp files.

Answer 3

Store the dictionary in a text file, one word per line. Then add this code to your program:

{ 
  std::string inputFileName;
  std::ifstream inputFile(inputFileName);
  std::string word;
  while( std::getline(inputFile, word) )
    dict.push_back(word);
}

Answer 4

Would it be possible to load only a single set of the dictionary from file using methods in other answers, ie load only "a" words from file a.dic . Or do you need to have access to the entire dictionary at once?