The humble PRINT statement

One of the first statements we learn in any language is the "print" statement. It is the core of the "Hello, world!" program. We normally learn it and then discard it, focussing our efforts on database and web service calls.

But the lowly "print" statement has its uses, as I was recently reminded.

I was working on a project with a medium-sized C++ application. We needed information to resolve several problems, information that would normally be available from the debugger and from the profiler. But the IDE's debugger was not usable (executing under the debugger would require a run time of about six hours) and the IDE did not have a profiler.

What to do?

For both cases, the PRINT statement (the "fprintf()" statement, actually, as we were using C++) was the thing we needed. A few carefully placed statements allowed use to capture the necessary information, make decisions, and resolve the problems.

The process wasn't that simple, of course. We needed several iterations, adding and removing PRINT statements in various locations. We also captured counts and timings of various functions.

The effort was worth it.

PRINT statements (or "printf()", or "print()", or "puts()", whatever you use) are useful tools. Here's how they can help:

• They can capture values of internal variables and state when the debugger is not available.
• They can capture lots of values of variables and state, for analysis at a level higher than the interactive level of the debugger. (Consider viewing several thousand values for trends in a debugger.)
• They can capture performance when a profiler is not available.
• They can extract information from the "release" version of software, because sometimes the problem doesn't occur in "debug" mode.

They may be simple, but they are useful. Keep PRINT statements in your toolbox.

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I was uncertain about the title for this column. I considered the C/C++ form of the generic statement ('printf()'). I also considered the general form used by other languages ('print()', 'puts()', 'WriteLine()'). I settled on BASIC's form of PRINT -- all capitals, no parentheses. All popular languages have such a statement; in the end, I suspect it matters little. Use what is best for you.