I am having some problems with some sample coding I have. Ideally I want a file that will have key words, that have data (int and strings) associated with them that can be changed. I will have duration (int), destination(string), and source(source) that can be edited at any time. This will be ultimately for ease of use backing up files for a set time in days, where they are and where they are going.
This is the sample code I have, I have fixed quit a few errors but am stuck on the last couple. Or is there an easier way about doing this? Sorry its all jumbled, I am pretty new C++...
Thank you for the help, I know its a lot to go through. Maybe someone has a good tutorial on easy configuration file parsing I could read up on also?
My gcc version is 4.4.7
The errors I am recieving are:
g++ configFile.cpp configFile.cpp:36: error: explicit specialization in non-namespace scope ‘class Convert’ configFile.cpp: In static member function ‘static T Convert::string_to_T(const std::string&)’: configFile.cpp:31: error: there are no arguments to ‘exitWithError’ that depend on a template parameter, so a declaration of ‘exitWithError’ must be available configFile.cpp:31: note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated)
#include <iostream>
#include <string>
#include <sstream>
#include <map>
#include <fstream>
#include <vector>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
class Convert
{
public:
template <typename T>
static std::string T_to_string(T const &val)
{
std::ostringstream ostr;
ostr << val;
return ostr.str();
}
template <typename T>
static T string_to_T(std::string const &val)
{
std::istringstream istr(val);
T returnVal;
if (!(istr >> returnVal))
exitWithError("CFG: Not a valid " + (std::string)typeid(T).name() + " received!\n");
return returnVal;
}
template <>
static std::string string_to_T(std::string const &val)
{
return val;
}
};
void exitWithError(const std::string &error)
{
std::cout << error;
std::cin.ignore();
std::cin.get();
exit(EXIT_FAILURE);
}
class ConfigFile
{
private:
std::map<std::string, std::string> contents;
std::string fName;
void removeComment(std::string &line) const
{
if (line.find(';') != line.npos)
line.erase(line.find(';'));
}
bool onlyWhitespace(const std::string &line) const
{
return (line.find_first_not_of(' ') == line.npos);
}
bool validLine(const std::string &line) const
{
std::string temp = line;
temp.erase(0, temp.find_first_not_of("\t "));
if (temp[0] == '=')
return false;
for (size_t i = temp.find('=') + 1; i < temp.length(); i++)
if (temp[i] != ' ')
return true;
return false;
}
void extractKey(std::string &key, size_t const &sepPos, const std::string &line) const
{
key = line.substr(0, sepPos);
if (key.find('\t') != line.npos || key.find(' ') != line.npos)
key.erase(key.find_first_of("\t "));
}
void extractValue(std::string &value, size_t const &sepPos, const std::string &line) const
{
value = line.substr(sepPos + 1);
value.erase(0, value.find_first_not_of("\t "));
value.erase(value.find_last_not_of("\t ") + 1);
}
void extractContents(const std::string &line)
{
std::string temp = line;
temp.erase(0, temp.find_first_not_of("\t "));
size_t sepPos = temp.find('=');
std::string key, value;
extractKey(key, sepPos, temp);
extractValue(value, sepPos, temp);
if (!keyExists(key))
contents.insert(std::pair<std::string, std::string>(key, value));
else
exitWithError("CFG: Can only have unique key names!\n");
}
void parseLine(const std::string &line, size_t const lineNo)
{
if (line.find('=') == line.npos)
exitWithError("CFG: Couldn't find separator on line: " + Convert::T_to_string(lineNo) + "\n");
if (!validLine(line))
exitWithError("CFG: Bad format for line: " + Convert::T_to_string(lineNo) + "\n");
extractContents(line);
}
void ExtractKeys()
{
std::ifstream file;
file.open(fName.c_str());
if (!file)
exitWithError("CFG: File " + fName + " couldn't be found!\n");
std::string line;
size_t lineNo = 0;
while (std::getline(file, line))
{
lineNo++;
std::string temp = line;
if (temp.empty())
continue;
removeComment(temp);
if (onlyWhitespace(temp))
continue;
parseLine(temp, lineNo);
}
file.close();
}
public:
ConfigFile(const std::string &fName)
{
this->fName = fName;
ExtractKeys();
}
bool keyExists(const std::string &key) const
{
return contents.find(key) != contents.end();
}
template <typename ValueType>
ValueType getValueOfKey(const std::string &key, ValueType const &defaultValue = ValueType()) const
{
if (!keyExists(key))
return defaultValue;
return Convert::string_to_T<ValueType>(contents.find(key)->second);
}
};
int main()
{
ConfigFile cfg("config.cfg");
bool exists = cfg.keyExists("car");
std::cout << "car key: " << std::boolalpha << exists << "\n";
exists = cfg.keyExists("fruits");
std::cout << "fruits key: " << exists << "\n";
std::string someValue = cfg.getValueOfKey<std::string>("mykey", "Unknown");
std::cout << "value of key mykey: " << someValue << "\n";
std::string carValue = cfg.getValueOfKey<std::string>("car");
std::cout << "value of key car: " << carValue << "\n";
double doubleVal = cfg.getValueOfKey<double>("double");
std::cout << "value of key double: " << doubleVal << "\n\n";
std::cin.get();
return 0;
}
