Warns of possible problems with string input and output format specifications. Functions diagnosed are printf, scanf, strftime, strfmon family functions and functions marked with format attributes.
where suboptions are:
all Turns on all format diagnostic messages. exarg Warns if excess arguments appear in printf and scanf style function calls. nlt Warns if a format string is not a string literal, unless the format function takes its format arguments as a va_list. sec Warns of possible security problems in use of format functions. y2k Warns of strftime formats that produce a 2-digit year. zln Warns of zero-length formats.
- Note:
- Specifying no in front of any of the above suboptions disables that group of diagnostic messages. For example, to turn off diagnostic messages for y2k warnings, specify -qformat=noy2k on the command line.
If -qformat is not specified on the command line, the compiler assumes a default setting of -qnoformat, which is equivalent to -qformat=noall.
If -qformat is specified on the command line without any suboptions, the compiler assumes a default setting of -qformat=all.
To enable all format string diagnostics, enter either of the following:
xlc++ myprogram.C -qformat=allxlc++ myprogram.C -qformat
xlc++ myprogram.C -qformat=all:noy2k