C++ string from file

small_ticket · #1 04-Jan-2005, 20:08

hi everyone!
i have a code that reads from a text file and according to the

CPP / C++ / C Code:

char komut[10]

it does some specific operations.

CPP / C++ / C Code:

//ifstream constrctır opens the file
	ifstream inClientFile ( "tester1.txt", ios::in );

	//exitprogram if ifstream could not open file
	if(!inClientFile ) {
		cerr << "File could not be opened" <<endl;
		exit(1);
	} 


	int lineNo;
	char komut[10];
	char string[40];

	cout <<left<< setw(10) << "lineNo" << setw(13) << "komut" <<" string" << endl << fixed << showpoint;

	//display each line
	while(inClientFile >> lineNo >> komut >> string){
             switch(*komut) {
		case 'Print':
			cout << string <<endl ;
			break;
		case 'Input':
			cout << "?"<< endl;
			int x;
			cin >> x;
			break;
		case 'End':
			exit(1);
		}
	}

My problem is when my string have whitespaces it reads until there but i want all until the end of the line. and then after i take the string if my string is somthing like

CPP / C++ / C Code:

u=x+y

how could i seperate this string and use this variables with their own values??
thanks!!

WaltP · #2 04-Jan-2005, 20:30

To read the entire line you can use getline() instead. the ">>" operator stops at whitespace.

small_ticket · #3 04-Jan-2005, 20:39

my text file is stg like this

00 Print give me 3 integers to operate
01 Input x
02 Input y
03 Input z
04 Let x=(x+y+z)/3
05 Print x
06 End

So actually i want to take them seperately as index, command and string but as the case like the first line i want to store all "give me 3 integers to operate" as string
what should i do for that case??
is it possible to take the first 2 with >> and then take them charachter by character till the end of the line?

dexter · #4 05-Jan-2005, 08:29

Based on the code you've got, I assume this is a basic interpreter.

Now, what you could do instead of,

CPP / C++ / C Code:

while(inClientFile >> lineNo >> komut >> string){

...is to have each case statement handle what is expected after the different types of komut... (especially if you intend to extend this interpreter further... you may have other tokens that don't require strings after them.)

So, instead:

CPP / C++ / C Code:

while(inClientFile >> lineNo >> komut){
    switch(*komut) {
    case 'Print':
      inClientFile.getline(string, 40, '\n');   // '\\n' not required as it is the default delimeter.
      cout << string <<endl ;
      break;

etc...

That said, your code in its current state will not compile... switch cases can't use strings to my knowledge... instead of using 'switch' I used 'if' and 'if else' statements with strcmp() tests when compiling the code.

Also, remeber to close your file at the end of the program...

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