Adding Verbosity to a Program - c++

Question

This is a very n00b question but
I'm writing a nix based tool and would like to have verbosity flags, based on the number of vvv's passed in I would go about printing debug/information statements in my program.
My question is how would I go about using opargs for this, since optargs can only parse one character at a time.
Also suppose I know I'm at verbosity level 3, do all my print statements have to be in an if condition? Or there a clever way of going about it using the pre-processor?
Also if someone could point me to some code online which does this, that would be awesome.
Thanks
I figure it out, thought I'd post here if someone else comes across this in the future:
Basically for all my different verbosity statements I defined a special print using the preprocessor like:
#define dprintf \
if (verbosity == 1) printf
I then put in the statements as needed in the code e.g.
dprintf ("Verbosity is at level 1.");
My opt atgs looks something like this
case 'v':
verbosity++;
break;

Answer 1

The verbosity level is not known at compile time so you need to have code ready to handle any level the user selects.
A simple, and easy to understand, way of doing this is to separate your logging functions in an opaque compilation unit with a static variable keeping track of the verbosity level. You then initialize this with something like "set_logging_level(level)" and write your logging functions guarded by this static variable. Then you only expose the initialization and the logging functions and use them as you need them in your code.
static level = 0;
void set_logging_level(int l) { level = l; }
void log_info(char* msg) {
// Will always print
}
void log_debug(char *msg) {
if(level > 0)
// Write to stdout or stderr, whichever fits
}
void log_details(char *msg) {
if(level > 1)
// As above
}
void log_insanity(char *msg) {
if(level > 2)
// As above
}
Edit: Saner conditions for logging. Especially if you want inclusive logging when the verbosity level goes up...

Answer 2

How about Conditional compilation?
You could also simplify by setting a number for verbose level instead of passing that many v's.
#if VERBOSE_LEVEL == 3
print("A verbose message");
#endif

Answer 3

I'm not too sure if this is what you've meant, but this is how I implemented it in another project:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define TRUE 1
#define FALSE 0
int usage( char *name, int quit );
int main (int argc, char **argv) {
int c;
static int vlevel = 0;
while ( (c = getopt(argc, argv, ":abc:d:hv012")) != -1) {
int this_option_optind = optind ? optind : 1;
switch (c) {
case 'v':
vlevel++;
printf ("verbosity level is %d\n", vlevel);
break;
case ':': /* Option without required operand */
fprintf(stderr, "option -%c requires an operand\n", optopt);
break;
case 'h':
case '?':
usage( argv[0], TRUE );
break;
default:
printf ("?? getopt returned character code 0%o ??\n", c);
}
}
if (optind < argc) {
printf ("non-option ARGV-elements:\n");
while (optind < argc)
printf ("\t%s\n", argv[optind++]);
}
exit (0);
}
int usage( char *progname, int quit )
{
printf ( "Usage:\n\t%s [-vh]\n", progname );
if ( quit ) exit( 1 );
return 0;
}
This would give you something like the following:
eroux#smaug:~$ ./testverbose -h
Usage:
./testverbose [-vh]
eroux#smaug:~$ ./testverbose -vvvv
verbosity level is 1
verbosity level is 2
verbosity level is 3
verbosity level is 4
eroux#smaug:~$
From there you should be able to use the vlevel variable [in main()] to print the correct message during the relevant verbosity level.