Thread: getline function is being weird

Code:

char dataIn[80];
char m[30] = "222222"
char cS[30] = "CCCC"
	while (!ins.eof()){

	ins.getline(dataIn, '\n');
	outs << m + cS + dataIn << endl;

	}

the problem is it only inserts the dataIn once, i get the m, and cS every line, but the dataIn only outputs once.

the output looks something like this

Code:

    
222222CCCC
222222CCCC4444444444444444444444444
222222CCCC
222222CCCC
222222CCCC
.
.
.
// 2 is m   
// C is cS              <--- actual data is a variety of letters and numbers 
// 4 is dataIn

im almost 100% sure that it is because i am using getline wrong, but i dont know how i am using it wrong... im really stuck on this one.

You cannot add C style strings (character arrays). To combine strings in that way you must use strcat. Use the C++ string class instead.

Your use of getline is wrong. First, you should not use eof() to control the loop. Check the return value of getline. If it is false, then you've reached eof or some other error.

Second, there are two forms of getline. One works with C style strings like you have. That one takes the number of characters in the buffer as the second argument. So where you have '\n', the compiler is interpreting that as a number (probably 10 - the ASCII value of '\n') corresponding to how many characters to read in. The delimiter is the third argument to the function. There is another form of getline that works with C++ strings, that doesn't require the buffer size because strings grow automatically. That version takes the stream as the first parameter.

So my suggestion is to switch to the C++ string class and use the string version of getline. ILoveVectors has given a good example of this.

thanks a whole bunch guys, it works like a charm.