Null byte stops for `print` but not `strlen`, why?

Question

I was playing around with Dart strings and noticed this:

print("\x00nullbyte".length);
print("\x00nullbyte");

If you run this, you'll find that the length is 9, which includes the null byte. But there is no output.

Trusting Google engineers more than myself, programming-wise, I'm thinking there might be a reason for that. What could it be?

Answer 1

The Dart string has length 9, and contains all nine code units. NUL characters are perfectly valid in a Dart string. They are not valid in C strings though, where they mark the end of the string. When printing, the string is eventually converted to a C-string to call the system library's output function. At that point, the system library sees only the NUL character and prints nothing.

Try:

main() { print("ab\x00cd"); }  // prints "ab".

The String.length function works entirely on the Dart String object, and doesn't go through the C strlen function. It's unaffected by the limits of C.

Arguably, the Dart print functionality should detect NUL characters and print the rest of the string anyway.