Question

I’m converting a double to a char string:

char txt[10];
double num;

num = 45.344322345

sprintf(txt, "%.1f", num);

and using “.1f” to truncate the decimal places, to the tenths digit.
i.e. – txt contains 45.3

I usually use precision in sprintf to ensure the char buffer is not overflowed.
How can I do that here also truncating the decimal, without using snprintf?

(i.e. if num = 345694876345.3 for some reason)

Thanks

EDIT If num is > buffer the result no longer matters, just do not want to crash. Not sure what would make the most sense in that case.

EDIT2 I should have made it more clear than in just the tag, that this is a C program.
I am having issues using snprintf in a C program. I don’t want to add any 3rd party libraries.

Answer 1

Use snprintf() , which will tell you how many bytes were not printed. In general, you should size your array to be large enough to handle the longest string representation of the target integer type. If not known in advance, use malloc() (or asprintf(), which is non-standard, but present on many platforms).

Edit

snprintf() will fail gracefully if the format exceeds the given buffer, it won’t overflow. If you don’t need to handle that, then simply using it will solve your problem. I can’t think of an instance where you would not want to handle that, but then again, I’m not working on whatever you are working on 🙂