string

[mahsaa]

why it gives string subscript out of range error?!

void main(vector<and> ands,vector<or> ors,vector<xor> xors,vector<nand>nands)
	 /////////////////////////reading file
{vector<string>help;
help.clear();
ifstream input;
input.open("test.txt");
string line;
while(!input.eof()){
	getline(input,line);
	help.push_back(line);
	line.clear();
}
input.close();

[3qX21hU5]

Well first off why are you declaring void main(vector<and> ands,vector<or> ors,vector<xor> xors,vector<nand>nands)

There can only be one main and that is not one of the ways to declare it. The simplest is this

int main()
{
    return 0;
}

That is all I wanted to comment on also please use codetags when posting code to the forums (Hint: Highlight code then press <> button)

[mahsaa]

I have classes named and,or...and in main I need their members so I declared main as those classes friend,do you mean that kind of declaring main is wrong?

[Daleth]

If you need to use the classes, just declare within the main block.

int main(){
      //And the alternative vector <foo> bar; for your containers too.
      and ands;
      or ors;
      xor xors;
      nand nands;
     //...Whatever code
}

Also, did you just forget to include the closing bracket to your main when copy/pasting?

[mahsaa]

yes,I just forgot that bracket in copy pasting.
I changed the way of declaring main function as you said.but my code still have that previous error!

[mahsaa]

is there any problem in my algorithm for reading from file and putting in string?!

[Chervil]

This loop is flawed:

while (!input.eof())
{
    getline(input,line);
    help.push_back(line);
    line.clear();
}

at line 3 (above), the getline is performed. But regardless of whether or not it was successful, the next two lines are executed - in particular the push_back() which may add an empty line to the vector.

A recommended way is to not use eof() at all.

    while (getline(input,line))
    {
        help.push_back(line);
    }