c++ - How to create a wrapper on printf? -

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• call printf using va_list 4 answers

i want write conditional printf, this

class conditionalprintf { public:     conditionalprintf(bool print)         : print_(print)     {}     void printf(int x, double y, char b, const char* format, ...) const    {         // use x, y , b          va_list argptr;         va_start(argptr, format);          if (print_)             printf(format, argptr);          va_end(argptr);    }  private:    bool print_; }; 

but prints garbage. there wrong? may implicit parameter change things?

also, if isn't idea whatsoever, other solutions there? don't want write if (print) printf(...) billion times.

vprintf forwards arg list printf

#include <stdio.h> #include <stdarg.h>  class conditionalprintf { public:     conditionalprintf(bool print)         : print_(print)     {}     void printf(int x, double y, char b, const char* format, ...) const    {         // use x, y , b          va_list argptr;         va_start(argptr, format);          if (print_)             vprintf(format, argptr);          va_end(argptr);    }  private:    bool print_; };