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With any variadic function, the function must know how to interpret the variable arguments list. With the printf() or scanf() functions, the format string tells the function what to expect. The simplest technique is to pass an explicit count of the other arguments (which are normally all the same ...

With any variadic function, the function must know how to interpret the variable arguments list. The “traditional” approach (exemplified by printf) is to specify number of arguments up front. However, this is not always a good idea: /* First argument specifies the number of parameters; the remaind...

One common use of variable-length argument lists is to implement functions that are a thin wrapper around the printf() family of functions. One such example is a set of error reporting functions. errmsg.h #ifndef ERRMSG_H_INCLUDED #define ERRMSG_H_INCLUDED #include <stdarg.h> #include...

Using a format string provides information about the expected number and type of the subsequent variadic arguments in such a way as to avoid the need for an explicit count argument or a terminator value. The example below shows a a function that wraps the standard printf() function, only allowing f...