// Program shows copying one text file from source location
// to any other location (destination), plus possibility of changing its name,
// and also shows many language features in exception handling.
// This program should be run from the command prompt

include<iostream>
include<stdio.h>
include<stdexcept>
using namespace std;
class PathError : public runtime_error
{
    public:
        PathError(const char *x) : runtime_error(x)
    {}
};
// function to open source file for read
FILE source (char argvs[])
{
    FILE *in;
    //open source file for read
    if((in = fopen(argvs[1],"r"))==NULL)
    {
        throw PathError("attempted to open wrong input file path");//terminate function
    }
    return in;
}
//function to create destination file for writting
FILE destination (char argvs[])
{
    FILE *out;
    //open destination file for write
    if((out = fopen(argvs[2],"w")) == NULL)
    {
        throw PathError("attempted to open wrong output file path");//terminate function
    }
    return out;
}
int main(int argc, char argv[])
{
    FILE in, *out;
    bool flag = 1;
    int temp;
    while(argc == 3)
    {
        try
        {
            in = source( argv );
            out = destination( argv );
            argc = 0;
        }
        catch(PathError& PathError)
        {
            cerr <<"\nException occured: " << PathError.what() << endl;
            return -1;
        }

    while(!feof(in))//test for it is not end of input file
    {
        temp = fgetc(in);//get char from (in)file
        if( temp != EOF)
        {
            fputc(temp,out);//put char to (out) file
        }
    }
    fclose(in);
    fclose(out);
    cout<<"\n\t 1 file copied.\n";
    flag = 0;
}
if( flag != 0 )
{
    cerr<<"\nWrong argument list!!!\n\n";
    return -1;
}
return 0;

}</pre>