vfprintf (C) David K.
The issue here is that vfprintf is a function that is supposed to behave the same as printf in that it is a function with a format string that gets passed to it, but which actually does the printing. The problem, however, is that we are unable to use printf in this instance. The compiler tries to figure out if there is a format string to use for format 0x402169, but vfprintf is a macro that is expanded only once.
So now all we do is take a string containing the format string, convert it to a pointer value, and pass this memory address to vfprintf. If the vfprintf function doesn’t have a format string, it just creates an empty string. This memory address is what our program will be printing to stdout. So the problem here is that the compiler doesn’t know if the first argument of vfprintf is a pointer or a string.
It is likely that the compiler would know this, especially if we are using a vfprintf.
So we need to make the compiler do what the compiler should be doing. The standard says that we should be passing a pointer, not a string.
But there is one more problem here. If we pass a pointer and the standard says that it is a string, then the compiler is bound to write the address of a variable called a at the top of the function. But this address is only valid for as long as we are calling the function and we are passing a pointer to something.
The main reason why we need to do that is because we cannot pass a pointer to a std::string until we know the address of the string. So we need to pass a pointer to a std::string to pass it to our compiler. Because of that we need to pass three things: a pointer, a string, and a std::string. The compiler then complains.
The reason that we need to pass this pointer is that we need to pass an address to a string to the compiler so that its address can be checked for an error. So because we need to pass these three things to the compiler it is no longer valid to pass strings to the compiler. This is not a new problem. It is an old problem.
This problem has been present in the C language since the early 90s. The C compiler was originally written for MIPS, and had to be modified to be the C compiler for a new architecture. There is an even older problem with the C compiler in general. It doesn’t check for errors. It just passes all the data to the compiler. This happens before any code runs.