al_ustr_vappendf
bool al_ustr_vappendf(ALLEGRO_USTR *us, const char *fmt, va_list ap)
Introduced in 5.0.0
Like al_ustr_appendf but you pass the variable argument list directly, instead of the arguments themselves. See al_ustr_newf about the "%s" and "%c" specifiers.
Returns true on success, false on error.
See also: al_ustr_appendf
Examples: ex_utf8
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