On Wednesday, 2 March 2016 at 04:12:13 UTC, Mike Parker wrote:
On Wednesday, 2 March 2016 at 01:39:13 UTC, David G. Maziero
wrote:
Consider the following function:
void RenderText( FontBMP font, int x, int y, const char* text )
{
for( int r=0; text[r]!='\0'; ++r )
{
You're asking for trouble here. There's no guarantee that any D
string is going to be null terminated. String literals are, but
beyond that, all bets are off.
char[256] text;
sprintf( &text[0], "Player: pos:%.3f - speed:%.3f",
player.position, player.speed );
Instead of sprintf, look into using std.format.sformat [1] (see
below). It's equivalent to std.format.format, but allows you to
provide a buffer.
RenderText( font, 0, 0, cast(char*)text );
It's considered bad form to cast an array to a pointer like
this. If you need a pointer to an array, just use the ptr
property: text.ptr. Always be aware of the null terminator
situation, though, when passing to C.
I could simply do "RenderText(font,0,0,"FPS:
"~to!string(fps));"
Won't compile without using the .ptr property (or casting,
which again, you shouldn't do). Moreover, you run into the null
terminator problem. "FPS :" will be null terminated because
it's a literal, but the string produced by concatentating it
with the result of to!string would not be.
Read https://dlang.org/spec/arrays.html#strings and try to use
std.string.toStringz
(http://dlang.org/phobos/std_string.html#.toStringz)
