Logging headaches

[homer_3]

Let's say I have a log function

void my_log(char * msg, unsigned int arg)
{
  char buf[500];
  snprintf(buf, 500, msg, arg);
  
  printf(buf);
}

So I can do something like

int val = 3;
my_log("Value = %d.\n", (unsigned int)val)

And I'll get the output "Value = 3." But what if I want to log a floating point value? When I try

float val = 46.666666667f;
my_log("Value = %f.\n", (unsigned int)val)

I get -0.000000 output. At the very least, I would have expected to get 46.0000.

So how would I have a wrapper logging function that would let me pass both floats and non-floats to it? One thought is to build the string beforehand, but my logger also has log levels and will avoid string construction if the logger isn't at the correct level since building a string can be expensive, especially if it's not even going to end up getting logged.

Of course, another thought is to have a different prototype, but this example is simplified and my logger takes up to 10 args to be formatted into the string. So that would be a lot of combinations of prototypes, not to mention all the basically duplicated code it would create.

Anyone else run into this before? What did you do?

[homer_3]

So, like usual, even though I spent 45 making my post and thinking about other ways to solve the issue before posting, it's not until just after I post that I solve the problem. I forgot that templates work on functions (not just classes). I made a templated function and now I can log whatever I want.

[Elysia]

Why are you using snprintf, char*, C-style char arrays and C-style (dangerous) formatting in C++?
Do you realize there are better alternatives?

[Neo1]

You should look into Boost.Log. Very easy to use, and if you need it, the advanced features are there.