CPP/IO/FileInput

FileInput.cpp

#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <sstream>
#include <cstdlib>
 
void ReadInt(const std::string &Filename);
void ReadIntStringDouble(const std::string &Filename);
void VectorOfLines(const std::string &Filename);
void SkipComments(const std::string &Filename);
 
 
/* Example.txt
23
test
4.5
*/
 
int main(int argc, char *argv[])
{
  /*
   * Read the filename from the command-line argument.
   * argv[0] is the EXE name
   */
  std::string Filename = argv[1];
 
  ReadInt(Filename);
  //ReadIntStringDouble(Filename);
  //VectorOfLines(Filename);
  //SkipComments(Filename);
  return 0;
}
 
void ReadInt(const std::string &Filename)
{
  std::cout << "Filename: " << Filename << std::endl;
 
  int Integer;
 
  //Create an input stream for file
  std::ifstream fin(Filename.c_str());
 
  /*
   * If our attempt to open the file has failed
   * then display error & exit returning -1 
   */
  if(!fin )
  {
  std::cout << "File not found!" << std::endl;
  exit(-1); 
  }
 
  std::string line;
  std::stringstream linestream;
 
  getline(fin, line);
  linestream.clear();
  linestream << line;
  linestream >> Integer;	
 
  fin.close();
 
  std::cout << "Integer: " << Integer << std::endl;
}
 
void ReadIntStringDouble(const std::string &Filename)
{
  std::cout << "Filename: " << Filename << std::endl;
 
  int Integer;
  std::string String;	
  double Double;
 
  std::ifstream fin(Filename.c_str());
 
 
  if(fin == NULL)
  {	
    std::cout << "Cannot open file." << std::endl;
  }
 
  std::string line;
  std::stringstream linestream;
 
  getline(fin, line);
  linestream.clear();
  linestream << line;
  linestream >> Integer;	
 
  getline(fin, line);
  linestream.clear();
  linestream << line;
  linestream >> String;
 
  getline(fin, line);
  linestream.clear();
  linestream << line;
  linestream >> Double;
 
  fin.close();
 
  std::cout << "Integer: " << Integer << std::endl;
  std::cout << "String: " << String << std::endl;
  std::cout << "Double: " << Double << std::endl;
}
 
void VectorOfLines(const std::string &Filename)
{
 
  std::ifstream fin(Filename.c_str());
 
  if(fin == NULL)
  {
    std::cout << "Cannot open file." << std::endl;
  }
 
  std::vector<std::string> Lines;
  std::string line;
 
  while(getline(fin, line))
  {
    Lines.push_back(line);
  }
 
  for(unsigned int i = 0; i < Lines.size(); i++)
  {
    std::cout << Lines[i] << std::endl;
  }
 
}
 
void SkipComments(const std::string &Filename)
{
  /* test.txt
  P3
  # example comment
  512 512
  255
 
  */
  std::ifstream fin(Filename.c_str());
 
  if(fin == NULL)
  {
    std::cout << "Cannot open file." << std::endl;
  }
 
  char MV[2];//the first 2 ascii values
  int width, height;
  int MPV;//max pixel value
 
  std::string line;
 
  getline(fin, line); //get first line
 
  MV[0] = line[0];
  MV[1] = line[1];
  std::cout << "MV[0] = " << MV[0] << std::endl;
  std::cout << "MV[1] = " << MV[1] << std::endl;
 
  line = "";
  getline(fin, line); //get second line
  std::string FirstChar = line.substr(0, 1);
 
  if(FirstChar == "#")
  {
    std::cout << "Skipped this line." << std::endl;
  }
 
  line = "";
  getline(fin, line); //get third line
  std::stringstream LineStream;
  LineStream << line;
  LineStream >> width >> height;
  std::cout << "Width = " << width << std::endl;
  std::cout << "Height = " << height << std::endl;
  LineStream.str("");
 
  line = "";
  getline(fin, line); //get fourth line
 
  LineStream.str("");
  LineStream.clear();
  LineStream << line;
  LineStream >> MPV;
 
  std::cout << "MPV = " << MPV << std::endl;
 
}