c++ help

[tkud]

Since i am learning c++ myself and only have access to ebooks(no credit card to buy books), i ask a lot of questions
so please bear with me.
Take a look at the following code:

//: C04:Cppcheck.cpp
// Configures .h & .cpp files to conform to style
// standard. Tests existing files for conformance.
#include <fstream>
#include <sstream>
#include <string>
#include <cstddef>
#include "require.h"
using namespace std;
 
bool startsWith(const string& base, const string& key) {
  return base.compare(0, key.size(), key) == 0;
}
 
void cppCheck(string fileName) {
  enum bufs { BASE, HEADER, IMPLEMENT, HLINE1, GUARD1,
    GUARD2, GUARD3, CPPLINE1, INCLUDE, BUFNUM };
  string part[BUFNUM];
  part[BASE] = fileName;
  // Find any '.' in the string:
  size_t loc = part[BASE].find('.');
  if(loc != string::npos)
    part[BASE].erase(loc); // Strip extension
  // Force to upper case:
  for(size_t i = 0; i < part[BASE].size(); i++)
    part[BASE][i] = toupper(part[BASE][i]);
  // Create file names and internal lines:
  part[HEADER] = part[BASE] + ".h";
  part[IMPLEMENT] = part[BASE] + ".cpp";
  part[HLINE1] = "//" ": " + part[HEADER];
  part[GUARD1] = "#ifndef " + part[BASE] + "_H";
  part[GUARD2] = "#define " + part[BASE] + "_H";
  part[GUARD3] = "#endif // " + part[BASE] +"_H";
  part[CPPLINE1] = string("//") + ": " + part[IMPLEMENT];
  part[INCLUDE] = "#include \"" + part[HEADER] + "\"";
  // First, try to open existing files:
  ifstream existh(part[HEADER].c_str()),
           existcpp(part[IMPLEMENT].c_str());
  if(!existh) { // Doesn't exist; create it
    ofstream newheader(part[HEADER].c_str());
    assure(newheader, part[HEADER].c_str());
    newheader << part[HLINE1] << endl
              << part[GUARD1] << endl
              << part[GUARD2] << endl << endl
              << part[GUARD3] << endl;
  } else { // Already exists; verify it
    stringstream hfile; // Write & read
    ostringstream newheader; // Write
    hfile << existh.rdbuf();
    // Check that first three lines conform:
    bool changed = false;
    string s;
    hfile.seekg(0);
    getline(hfile, s);
    bool lineUsed = false;
    // The call to good() is for Microsoft (later too):
    for(int line = HLINE1; hfile.good() && line <= GUARD2;
         ++line) {
      if(startsWith(s, part[line])) {
        newheader << s << endl;
        lineUsed = true;
        if(getline(hfile, s))
          lineUsed = false;
      } else {
        newheader << part[line] << endl;
        changed = true;
        lineUsed = false;
      }
    }
    // Copy rest of file
    if(!lineUsed)
      newheader << s << endl;
    newheader << hfile.rdbuf();
    // Check for GUARD3
    string head = hfile.str();
    if(head.find(part[GUARD3]) == string::npos) {
      newheader << part[GUARD3] << endl;
      changed = true;
    }
    // If there were changes, overwrite file:
    if(changed) {
      existh.close();
      ofstream newH(part[HEADER].c_str());
      assure(newH, part[HEADER].c_str());
      newH << "//@//\n"  // Change marker
           << newheader.str();
    }
  }
  if(!existcpp) { // Create cpp file
    ofstream newcpp(part[IMPLEMENT].c_str());
    assure(newcpp, part[IMPLEMENT].c_str());
    newcpp << part[CPPLINE1] << endl
           << part[INCLUDE] << endl;
  } else { // Already exists; verify it
    stringstream cppfile;
    ostringstream newcpp;
    cppfile << existcpp.rdbuf();
    // Check that first two lines conform:
    bool changed = false;
    string s;
    cppfile.seekg(0);
    getline(cppfile, s);
    bool lineUsed = false;
    for(int line = CPPLINE1;
        cppfile.good() && line <= INCLUDE; ++line) {
      if(startsWith(s, part[line])) {
        newcpp << s << endl;
        lineUsed = true;
        if(getline(cppfile, s))
          lineUsed = false;
      } else {
        newcpp << part[line] << endl;
        changed = true;
        lineUsed = false;
      }
    }
    // Copy rest of file
    if(!lineUsed)
      newcpp << s << endl;
    newcpp << cppfile.rdbuf();
    // If there were changes, overwrite file:
    if(changed) {
      existcpp.close();
      ofstream newCPP(part[IMPLEMENT].c_str());
      assure(newCPP, part[IMPLEMENT].c_str());
      newCPP << "//@//\n"  // Change marker
             << newcpp.str();
    }
  }
}
 
int main(int argc, char* argv[]) {
  if(argc > 1)
    cppCheck(argv[1]);
  else
    cppCheck("cppCheckTest.h");
} ///:~

Can someone explain the following for me: getline(),<ctime>,<iosfwd>,good(),c_str()?
I would be very grateful.

[niXman]

All about STL you may find at: http://www.cplusplus.com/reference/

[Kontained]

Getline() is used to grab whole strings, including white space. I use it most often for reading information from a file. So if you had a file named "example.txt" and you wanted to store the information in string line, you would use...

ifstream inData;
        inData.open("example.txt");

        while (getline(inData, line))
        {
                //code that works with line
         }

ifstream is used for opening a file.
The above code will get each line in "example.txt" one by one. For example, if the first line in the text file was "My name is bob" it would store that into the string line.

I use <ctime> most often for generating random numbers. But thats not all <ctime> can be used for. <ctime> info

c_str() is used to convert a c++ string to a c string. c_str info

<iosfwd> I've never used this header so I can not shed much light on it.

[tkud]

thanks for the explanation, but sorry i meant its use in the code,i.e c_str,
thanks