remove beginning and end whitespace

[afra]

hi heys, i am trying to remove beginning and the end whitespace in one file, and output the result to another file. But i am confused about how to remove whitespace. i need to make a function to do it. It should use string, anyone can help me ?
here is my code.

#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <fstream>

using namespace std;
void IsFileName(string filename);

int main(int argc, char const *argv[]) {
string inputfileName = argv[1];
ifstream inStream;
inStream.open("first.txt");
IsFileName(inputfileName);

string outputfileName = argv[2];
ofstream outStream;
outStream.open("second.txt");
IsFileName(outputfileName);

string line;
while (getline(inStream, line))
{
cout << line << endl;
outStream << line <<endl;
}

inStream.close();
outStream.close();

/*add code*/
return 0;
}// main

void IsFileName(string filename){
ifstream inStream;
inStream.open(filename.c_str());
if (inStream.fail()){
cout << "Error opening the file"<<endl;
exit(0);
}
}

[lastchance]

You are multiply confused. You appear to try to open two input files: one in main() and the other via a function. You do nothing with the latter. Similarly with output.

Please explain more clearly exactly what white space you are trying to remove.

Please use code tags when posting code.

[jonnin]

Here is a simple trim routine. if you want to keep all the internals instead, you can replace that bit with a substring and it would be simpler and faster. I am sure it can be made better; as I said, it is a quick/simple one.

void trim(string &s, char c, bool keepinternal = true)
{  //keepinternal true means keep one copy of multiples inside 
//while false means to remove all copies.  ALL leading and trailing (even multiples)
//are removed regardless. 
  size_t dx; size_t i; size_t j; 
  if(keepinternal == false)
  { //completely eliminates the character c from the string.   
  	s.erase(std::remove(s.begin(), s.end(), c), s.end());
	return;
  }  
  //trim leading and trailing and internal
  dx = 0;   i = s.length()-1;   
  while(s[dx] == c) {dx++;} //find the first letter that is not c
  while(s[i] == c) {i--;} //find the last letter that is not c  
  string temp = s;  s = ""; //copy s into temp and set s to empty string
  for(j = dx; j<i+1; j++)
  { //for all the letters between the first not c up to the last not c, copy back into s
    //unless there are 2+ in a row, then only get the first one. 
	if(temp[j]!=c || (temp[j]==c && temp[j+1]!=c))//keeps 1 copy per group of 1 or more cs internally
	s += temp[j]; 
  }
}