Question

After excellent advice I defined a struct, filled it with data read from a file and pushed it on a vector. Nice!!! Could somebody tell me now how I can call back the content of a member of the i-th struct I pushed on the vector?

The Structure definition:

struct Config_Data
{
    int Surf_Index;
    std::string Surf_Mnemo;
    double Surf_Param[5];
    std::string Surf_Comm;
};

Instantiation of the Struct and the definition of the vector:

Config_Data SURF;
std::vector<Config_Data> CDATA_SURF;

For filling the struct:

for (i=1;i<=10;i++)
{
    getline(INP_Stream, Line, delim_Config);
    SURF.Surf_Index=atoi(Line.c_str());

    getline(INP_Stream,SURF.Surf_Mnemo,delim_Config);
    SURF.Surf_Param[0]=Mnemo_list[SURF.Surf_Mnemo];
    for (j=1;j<=Mnemo_list[SURF.Surf_Mnemo];j++)
    {
        getline(INP_Stream,Line,delim_Config);
        SURF.Surf_Param[j]=strtod(Line.c_str(),NULL);
    }
    getline(INP_Stream, SURF.Surf_Comm,delim_Line);
    CDATA_SURF.push_back(SURF);
    cout<<CDATA_SURF.size()<<endl;
    string aaa=CDATA_SURF[i].Surf_Comm;
}

As you can see I read strings from a csv file. I am not so happy with the way I convert strings in the int or double types, but it seem to work.

The way I wanted to call the i-th struct in the vector and its member Surf_Comm:

std::string aaa=CDATA_SURF[i].Surf_Comm;   

I compiled without problems but at runtime I get segment violation signals. Being a beginner, I have no clue what is going on.

All help is very welcome!!!

Thanks in advance,

Regards,

Stefan

Answer 1

Element numeration in std::vector starts with zero value. Thus if vector holds one element, index of this value is 0. In case of two values – 0 and 1 and so on. Do not be confused by the size() vector method. It returns a number of holding elements.

So index of the newly pushed value equals to size()-1. Access to i-th element (that does not exist) results into an error.

This code should work if you change range of i value in cycle to for( i = 0; i < 10; i++ ).