CODEWITHSUNDEEP
c++debuggingcoutvariadic-functions
arnm
arnm

Reputation: 1765

C++ Best Way Of Outputting Formatted Variable Argument Lists

This is my current function which works but is not type safe and can get annoying sometimes.

void Debug::Log(LogLevel level, const char* format, ...)
{
va_list args;
va_start(args, format);
cout << "[" << LogLevelToString(level) << "]\t";
vprintf(format, args);
va_end(args);
cout << endl;
}

As you can see I would like for the arguments passed in to be formatted by the format specified. I know std::cout has formatting capabilities but I haven't found anything which explains how it can be implemented with the C va_list.

Basically the main points are: I want to keep the the same behavior but with a type safe more modern method, I need to std::cout so I can easily redirect output to file or where ever I need to.

Helpful points: from the format I can determine how many parameters where passed in, is there a way to loop through va_list arguments so I can pass them to cout individually?

Thanks

Upvotes: 2

Views: 1092

Answers (1)

n3rd4n1
n3rd4n1

Reputation: 371

For easy redirection, you can certainly use vfprintf(). For individual control/cout of each argument, I think the only way is to va_arg() through the list using the correct type, i.e. an_int = va_arg(the_va_list, int);, a_double = va_arg(the_va_list, double);, and so on. I haven't tried but I think va_arg will do the proper increment on the memory using the type passed to it.

Upvotes: 0

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