C++ library StringStream (for Serial.print)

Forum 2005-2010 (read only) Software Bugs & Suggestions
1

There is something amazingly cool in C++ programs: using streams for output. It's a lot easier than in C when you use printf-like functions.

Eg: You've got 2 variables in your code, you'd like to preview them:

var_1=42; var_2=47;
std::cout << "Variable 1 = " << var_1 << endl << "Variable 2 = " << var_2 << endl;

will give on a terminal:

Variable 1 = 42
Variable 2 = 47

Now imagine you want to do the same thing on the arduino, via Serial.print:

Serial.print("Variable 1 = ");
Serial.println(var_1, DEC);
Serial.print("Variable 2 = ");
Serial.println(var_2, DEC);

A bit longer..

As the Arduino software is C++ compatible, it could be possible to include some of the standard libraries, to enable this..

2

Franky, you may be interested in this thread: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1231224786

3

Ha! Yes, I still include this line in every sketch I use at home:

template<class T> inline Print &operator <<(Print &obj, T arg) { obj.print(arg); return obj; }

I agree it's pretty darn cool! :slight_smile:

Mikal

4

It's probably just because I'm not used to seeing it, but I find

std::cout << "Variable 1 = " << var_1 << endl << "Variable 2 = " << var_2 << endl;

to be almost unreadable. All those "<" characters confuse me - I prefer the long winded

Serial.print("Variable 1 = ");
Serial.println(var_1, DEC);
Serial.print("Variable 2 = ");
Serial.println(var_2, DEC);

Does anyone know if there's any difference in how many bytes each compiles to?

Andrew

5

Does anyone know if there's any difference in how many bytes each compiles to?

There is no difference, the same machine code would be produced by a stream version or seperate print statements.

6

There is no difference, the same machine code would be produced by a stream version or seperate print statements.

Thanks. I'll stick with the long-winded version then, which now I come to think of it is quite odd since I'm quite happy to write something like

pattern = ++pattern % numPatterns

I guess it really does come down to what you're used to (e.g. "where do the curly braces go?").

Andrew

7

Yeah, indeed that's cool for long serial data transmission, or for Terminal purpose using Serial Monitor...

I was first thinking about a printf function, with variable arguments, but as Arduino handles c++, streams are definitely a better way..

I will try this stuff, thanks guys!