Thread: converting string into char*

Hi,

I am having some problems. I started with c++ and so far am finding it a bit confusing. (But i'll get there). the problem i am having right now is, how to convert string to char* . I was told the memcpy is the fastest way but i cannot figure out why it is not working. Oh and is there some tutorial regarding string manipulations in c++.

Code:

#include <cstring>
#include <vector>
#include <fstream>
#include <iostream>


// Read a file into a vector

void help(char *program) {
  std::cout << program; 
  std::cout << ": Need a filename for a parameter.\n";
}

int main(int argc, char* argv[])
{
  if (argc < 2){ 
	help(argv[0]);
	return 1;
  }
  
  std::vector<std::string> file;
  std::string line;
  
  file.clear();
  std::ifstream infile (argv[1], std::ios_base::in);

  int size = 0;
  while (getline(infile, line, '\n')){
    file.push_back (line);
    size += line.length();
  }

  char *a;
  a = new char[size];
  for (int i = 0; i<file.size();i++){
	  memcpy(a[i+file[i].length()],file[i],file[i].length());
  }

  return 0;
}

so i need the lines i read from file to be in a char array since some other c function require it like that. Is there any better way to do this ??

thank you


P.S.
Here is the error:

Code:

 cannot convert ‘std::basic_string<char, std::char_traits<char>, std::allocator<char> >’ to ‘const void*’ for argument ‘2’ to ‘void* memcpy(void*, const void*, size_t)’

baxy