Calling a method from a different .cpp file

[VitaminG]

I want to save some data as a text file, the first txt file will contain header information, the other text file will save data streamed from sensors, so with the help from the internet I created the following "datalogger.cpp" file

#include "datalogger.h"
#include <QDebug>
#include <iostream>
#include <QFile>
 
DataLogger::DataLogger(QObject *parent) : QObject(parent)
   {
 
    }
 
   DataLogger::~DataLogger(){
 
    }
    void DataLogger::save(DataStream &input){
        saveAsText(input);
 
 
    }
    void DataLogger::saveAsText(DataStream &input){
 
                        QTextStream outHeader(&outFileHeader);
 
                        outHeader   << "[CAPTURE SETTINGS]\n"
                                    << "Filename: " <<      SettingsSingleton::instance().getFileName() << ".txt \n"
                                    << "Samples: " <<       QString::number(input.size()) << "\n"
                                    << "Duration: " <<      QString::number(input.back().time) << "ms \n"
                                    << "Sample rate: " <<   QString::number(SettingsSingleton::instance().getSampleRate()) << " Hz\n"
                                    << "Source: "  <<       SettingsSingleton::instance().getSource() << "\n"                                  
 
                        outFileHeader.close();
 
                    }
 
                    QFile outFile(SettingsSingleton::instance().getFileName() + ".txt");
 
                     QTextStream out(&outFile);                      
 
                        for (int i ; i<input.size();i++){
                               const EcgStreamObject tmp=input.at(i);
                                                out << tmp.toText() << endl; //"\n";    
 
                        }  
 
                        outFile.close();
                    }    
 
    }

#include "datalogger.h"
#include <QDebug>
#include <iostream>
#include <QFile>

DataLogger::DataLogger(QObject *parent) : QObject(parent)
   {
    
    }
    
   DataLogger::~DataLogger(){
    
    }
    void DataLogger::save(DataStream &input){
        saveAsText(input);
    

    }
    void DataLogger::saveAsText(DataStream &input){
                        
                        QTextStream outHeader(&outFileHeader);
    
                        outHeader   << "[CAPTURE SETTINGS]\n"
                                    << "Filename: " <<      SettingsSingleton::instance().getFileName() << ".txt \n"
                                    << "Samples: " <<       QString::number(input.size()) << "\n"
                                    << "Duration: " <<      QString::number(input.back().time) << "ms \n"
                                    << "Sample rate: " <<   QString::number(SettingsSingleton::instance().getSampleRate()) << " Hz\n"
                                    << "Source: "  <<       SettingsSingleton::instance().getSource() << "\n"                                  
    
                        outFileHeader.close();
    
                    }
    
                    QFile outFile(SettingsSingleton::instance().getFileName() + ".txt");
    
                     QTextStream out(&outFile);                      
    
                        for (int i ; i<input.size();i++){
                               const EcgStreamObject tmp=input.at(i);
                                                out << tmp.toText() << endl; //"\n";    
    
                        }  
   
                        outFile.close();
                    }    
    
    }

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I have my "DataStream" input variable that I want to pass to the method and save as a ".txt" file, however I do no know how to call the method "void DataLogger::save(DataStream &input)" from a different ".cpp" file where the DataStream variable is located.
I am extremely new to c++ please it as simple as possible please.
Thank you in advance

[ChrisW67]

#include "datalogger.h"
...
DataStream myDataStream;
...
DataLogger logger;
logger.save(myDataStream);

#include "datalogger.h"
...
DataStream myDataStream;
...
DataLogger logger;
logger.save(myDataStream);

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This assumes that DataLogger::save() is declared public.

[VitaminG]

How would I know if it is declared as public?
Orhow would I declare it as public?
Thanks for your reply

[d_stranz]

I think that instead of asking a lot of questions here about basic C++ things that you should already know -before- you start trying to use Qt, you should work your way through a C++ book or some of the many online C++ tutorials. Here is a good one, on a site I use all the time for C++ information.

This really is a forum for answering questions about Qt, not for teaching basic C++ concepts.