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POSegmentation Fault when trying to push a string to the back of a list
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copied!<p>I am trying to write a logger class for my C++ calculator, but I'm experiencing a problem while trying to push a string into a list.</p> <p>I have tried researching this issue and have found some information on this, but nothing that seems to help with my problem. I am using a rather basic C++ compiler, with little debugging utilities and I've not used C++ in quite some time (even then it was only a small amount).</p> <p>My code:</p> <pre><code>#ifndef _LOGGER_H_ #define _LOGGER_H_ #include <iostream> #include <list> #include <string> using std::cout; using std::cin; using std::endl; using std::list; using std::string; class Logger { private: list<string> mEntries; public: Logger() {} ~Logger() {} // Public Methods void WriteEntry(const string& entry) { mEntries.push_back(entry); } void DisplayEntries() { cout << endl << "**********************" << endl << "* Logger Entries *" << endl << "**********************" << endl << endl; for(list<string>::iterator it = mEntries.begin(); it != mEntries.end(); it++) { // *** BELOW LINE IS MARKED WITH THE ERROR *** cout << *it << endl; } } }; #endif </code></pre> <p>I am calling the WriteEntry method by simply passing in a string, like so:</p> <pre><code>mLogger->WriteEntry("Testing"); </code></pre> <p>Any advice on this would be greatly appreciated.</p> <p><strong>* CODE ABOVE HAS BEEN ALTERED TO HOW IT IS NOW *</strong></p> <p>Now, the line:</p> <pre><code>cout << *it << endl; </code></pre> <p>causes the same error. I'm assuming this has something to do with how I am trying to get the string value from the iterator.</p> <p>The code I am using to call it is in my main.cpp file:</p> <pre><code>#include <iostream> #include <string> #include <sstream> #include "CommandParser.h" #include "CommandManager.h" #include "Exceptions.h" #include "Logger.h" using std::string; using std::stringstream; using std::cout; using std::cin; using std::endl; #define MSG_QUIT 2384321 #define SHOW_LOGGER true void RegisterCommands(void); void UnregisterCommands(void); int ApplicationLoop(void); void CheckForLoggingOutput(void); void ShowDebugLog(void); // Operations double Operation_Add(double* params); double Operation_Subtract(double* params); double Operation_Multiply(double* params); double Operation_Divide(double* params); // Variable CommandManager *mCommandManager; CommandParser *mCommandParser; Logger *mLogger; int main(int argc, const char **argv) { mLogger->WriteEntry("Registering commands...\0"); // Make sure we register all commands first RegisterCommands(); mLogger->WriteEntry("Command registration complete.\0"); // Check the input to see if we're using the program standalone, // or not if(argc == 0) { mLogger->WriteEntry("Starting application message pump...\0"); // Full version int result; do { result = ApplicationLoop(); } while(result != MSG_QUIT); } else { mLogger->WriteEntry("Starting standalone application...\0"); // Standalone - single use // Join the args into a string stringstream joinedStrings(argv[0]); for(int i = 1; i < argc; i++) { joinedStrings << argv[i]; } mLogger->WriteEntry("Parsing argument '" + joinedStrings.str() + "'...\0"); // Parse the string mCommandParser->Parse(joinedStrings.str()); // Get the command names from the parser list<string> commandNames = mCommandParser->GetCommandNames(); // Check that all of the commands have been registered for(list<string>::iterator it = commandNames.begin(); it != commandNames.end(); it++) { mLogger->WriteEntry("Checking command '" + *it + "' is registered...\0"); if(!mCommandManager->IsCommandRegistered(*it)) { // TODO: Throw exception mLogger->WriteEntry("Command '" + *it + "' has not been registered.\0"); } } // Get each command from the parser and use it's values // to invoke the relevant command from the manager double results[commandNames.size()]; int currentResultIndex = 0; for(list<string>::iterator name_iterator = commandNames.begin(); name_iterator != commandNames.end(); name_iterator++) { string paramString = mCommandParser->GetCommandValue(*name_iterator); list<string> paramStringArray = StringHelper::Split(paramString, ' '); double params[paramStringArray.size()]; int index = 0; for(list<string>::iterator param_iterator = paramStringArray.begin(); param_iterator != paramStringArray.end(); param_iterator++) { // Parse the current string to a double value params[index++] = atof(param_iterator->c_str()); } mLogger->WriteEntry("Invoking command '" + *name_iterator + "'...\0"); results[currentResultIndex++] = mCommandManager->InvokeCommand(*name_iterator, params); } // Output all results for(int i = 0; i < commandNames.size(); i++) { cout << "Result[" << i << "]: " << results[i] << endl; } } mLogger->WriteEntry("Unregistering commands...\0"); // Make sure we clear up our resources UnregisterCommands(); mLogger->WriteEntry("Command unregistration complete.\0"); if(SHOW_LOGGER) { CheckForLoggingOutput(); } system("PAUSE"); return 0; } void RegisterCommands() { mCommandManager = new CommandManager(); mCommandParser = new CommandParser(); mLogger = new Logger(); // Known commands mCommandManager->RegisterCommand("add", &Operation_Add); mCommandManager->RegisterCommand("sub", &Operation_Subtract); mCommandManager->RegisterCommand("mul", &Operation_Multiply); mCommandManager->RegisterCommand("div", &Operation_Divide); } void UnregisterCommands() { // Unregister each command mCommandManager->UnregisterCommand("add"); mCommandManager->UnregisterCommand("sub"); mCommandManager->UnregisterCommand("mul"); mCommandManager->UnregisterCommand("div"); // Delete the logger pointer delete mLogger; // Delete the command manager pointer delete mCommandManager; // Delete the command parser pointer delete mCommandParser; } int ApplicationLoop() { return MSG_QUIT; } void CheckForLoggingOutput() { char answer = 'n'; cout << endl << "Do you wish to view the debug log? [y/n]: "; cin >> answer; switch(answer) { case 'y': ShowDebugLog(); break; } } void ShowDebugLog() { mLogger->DisplayEntries(); } // Operation Definitions double Operation_Add(double* values) { double accumulator = 0.0; // Iterate over all values and accumulate them for(int i = 0; i < (sizeof values) - 1; i++) { accumulator += values[i]; } // Return the result of the calculation return accumulator; } double Operation_Subtract(double* values) { double accumulator = 0.0; // Iterate over all values and negativel accumulate them for(int i = 0; i < (sizeof values) - 1; i++) { accumulator -= values[i]; } // Return the result of the calculation return accumulator; } double Operation_Multiply(double* values) { double accumulator = 0.0; for(int i = 0; i < (sizeof values) - 1; i++) { accumulator *= values[i]; } // Return the value of the calculation return accumulator; } double Operation_Divide(double* values) { double accumulator = 0.0; for(int i = 0; i < (sizeof values) - 1; i++) { accumulator /= values[i]; } // Return the result of the calculation return accumulator; } </code></pre> <hr>

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