Question

我在ubuntu 16.04.1LTS上下载了libconfig-1.4.9

并安装。 lib中包含的示例已成功通过。我将example1复制到另一个目录。编译

http://igor-zivkovic.from.hr/BLFS/general/libconfig.html

全成。运行

g++ example1.cpp -lconfig++ -Wall -o example1

我将此示例复制到另一台计算机，示例工作正常（先前使用sudo apt-get install（ubuntu 14.04LTS）安装了libconfig。）

example1.cpp

./example1: symbol lookup error: ./example1: undefined symbol: _ZNK9libconfig7SettingcvSsEv

example.cfg

#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <libconfig.h++>

using namespace std;
using namespace libconfig;

// This example reads the configuration file 'example.cfg' and displays
// some of its contents.

int main(int argc, char **argv)
{
  Config cfg;

  // Read the file. If there is an error, report it and exit.
  try
  {
    cfg.readFile("example.cfg");
  }
  catch(const FileIOException &fioex)
  {
    std::cerr << "I/O error while reading file." << std::endl;
    return(EXIT_FAILURE);
  }
  catch(const ParseException &pex)
  {
    std::cerr << "Parse error at " << pex.getFile() << ":" << pex.getLine()
              << " - " << pex.getError() << std::endl;
    return(EXIT_FAILURE);
  }

  // Get the store name.
  try
  {
    string name = cfg.lookup("name");
    cout << "Store name: " << name << endl << endl;
  }
  catch(const SettingNotFoundException &nfex)
  {
    cerr << "No 'name' setting in configuration file." << endl;
  }

  const Setting& root = cfg.getRoot();

  // Output a list of all books in the inventory.
  try
  {
    const Setting &books = root["inventory"]["books"];
    int count = books.getLength();

    cout << setw(30) << left << "TITLE" << "  "
         << setw(30) << left << "AUTHOR" << "   "
         << setw(6) << left << "PRICE" << "  "
         << "QTY"
         << endl;

    for(int i = 0; i < count; ++i)
    {
      const Setting &book = books[i];

      // Only output the record if all of the expected fields are present.
      string title, author;
      double price;
      int qty;

      if(!(book.lookupValue("title", title)
           && book.lookupValue("author", author)
           && book.lookupValue("price", price)
           && book.lookupValue("qty", qty)))
        continue;

      cout << setw(30) << left << title << "  "
           << setw(30) << left << author << "  "
           << '$' << setw(6) << right << price << "  "
           << qty
           << endl;
    }
    cout << endl;
  }
  catch(const SettingNotFoundException &nfex)
  {
    // Ignore.
  }

  // Output a list of all books in the inventory.
  try
  {
    const Setting &movies = root["inventory"]["movies"];
    int count = movies.getLength();

    cout << setw(30) << left << "TITLE" << "  "
         << setw(10) << left << "MEDIA" << "   "
         << setw(6) << left << "PRICE" << "  "
         << "QTY"
         << endl;

    for(int i = 0; i < count; ++i)
    {
      const Setting &movie = movies[i];

      // Only output the record if all of the expected fields are present.
      string title, media;
      double price;
      int qty;

      if(!(movie.lookupValue("title", title)
           && movie.lookupValue("media", media)
           && movie.lookupValue("price", price)
           && movie.lookupValue("qty", qty)))
        continue;

      cout << setw(30) << left << title << "  "
           << setw(10) << left << media << "  "
           << '$' << setw(6) << right << price << "  "
           << qty
           << endl;
    }
    cout << endl;
  }
  catch(const SettingNotFoundException &nfex)
  {
    // Ignore.
  }

  return(EXIT_SUCCESS);
}

// eof

编译libconfig ++程序

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