Separating Arguments for Multiple programs from Command line in main

Question

I am integrating 2 programs and turning them into one (I know, not ideal). I expect command line args to look something like

bin/programName -optionsProgram1 --optionsProgram2

I have parsed the options out so I now have the separate sets of arguments, shown below.

bin/programName -optionsProgram1
bin/programName --opionsProgram2

This is great, just how I need them to be. The problem is that I did that with arguments being pushed onto vectors and now I need to use pointers to character arrays. Can anyone recommend a way to convert my vectors into char* in a better way? Also, these will have to be returned as char** in the end, please keep that in mind with your answers.

I have tried using strncpy and realized there was a type error. My attempt is shown below

.h excerpt

std::vector<std::string> myVec; //hold the arguments, one at each pos
std::vector<char*> myCharArray; //intended location for result of conversion

.cpp excerpt

size_t vecSize = myVec.size()
size_t charVecSize;

myCharArray.resize(vecSize);
for(size_t i=0; i < vecSize; ++i)
{
    csize = myVec.size()+1 //include null
    myCharArray[i] = new char[csize]

    strncpy(myCharArray[i], myVec[i].c_str(), csize);
    myCharArray[i][csize-1] = '\0'
}

Answer 1

Try std::vector<const char*> populated with pointers from std::string::c_str() , eg:

std::vector<std::string> myVec;
std::vector<const char*> myCharArray;

// populate myVec as needed ...

...

// add +1 if you need the array to be null-terminated...
myCharArray.reserve(myVec.size()/*+1*/);
for (auto &s : myVec) {
    myCharArray.push_back(s.c_str());
}
//myCharArray.push_back(nullptr);

or:

myCharArray.resize(myVec.size()/*+1*/);
for (size_t i = 0; i < myVec.size(); ++i) {
    myCharArray[i] = myVec[i].c_str();
}
//myCharArray.back() = nullptr;

or:

#include <algorithm>
myCharArray.resize(myVec.size()/*+1*/);
std::transform(myVec.begin(), myVec.end(), myCharArray.begin(),
    [](std::string &s){ return s.c_str(); });
//myCharArray.back() = nullptr;

Then you can use myCharArray.data() (which is const char ** ) as needed.