制作我自己的printf功能？

Question

I was wondering how I could do this. I'm mostly puzzled by the N arguments part:

printf("Hello, I'm %i years old and my mom is %i .",me.age(),mom.age());

I want to make a function that will take a formatted string like this and return a std string.

How is the N arguments part done?

Answer 1

printf is a variadic function; you can implement your own variadic functions using the facilities provided by <stdarg.h> .

In C++, you should avoid variadic functions wherever possible. They are quite limited in what types they can accept as arguments and they are not type safe. C++0x adds variadic templates to C++; once support for this feature is widespread, you'll be able to write type safe variadic functions.

In the meantime, it's best to use some other type safe method. Boost.Format , for example, overloads the % operator to perform formatting.