The iostream and stdio libraries are often thought of as analogous and interchangeable. To a small degree, this is true but there are fundamental differences that every C++ programmer should understand. Because this is a common curiosity among many C++ programmers, the aim of this article is to clear things up between the two.
If one finds themselves often interchanging between these two libraries, it's safe to say that they are not completely versed in what is happening under the hood. As a robust language with extreme functionality, C++ is complex language and requires a good amount of insight. That being said, a good programmer is able to understand exactly what is going on with their code down to the specifics. This is what makes learning about the differences between these two libraries essential. Let's look at what makes these libraries unique, starting with the stdio library.
What is the stdio library's story? Long before C++ was ever invented, the stdio library was in full use. It was and still is the key to input and output streams in C. It holds all of the necessary functions for the user to interact with a program. These functions once were absolutely essential and cutting edge. Although they still have their uses today, we tend to use more up-to-date functions such as cout and cin, as opposed to printf and scanf.
It's important to note that, although the syntax for C is #include<stdio.h> when coding in C++ today, the standard is to write #include<cstdio>. These are both the same exact libraries; the syntax has simply been updated. The main advantage of including this library is that you will be able to use functions that were originally designed for C in your C++ code.
Are these functions important and necessary for a C++ programmer? In short, no. The best bet for the average C++ programmer is to simply use the iostream library. Consider stdio to be the foundation upon which iostream was built. It is ultimately up to the one writing the code as to which header file they would like to use, but iostream will most likely reduce errors, increase type safety, and provide inheritability. It is highly essential to be consistent throughout your program because using functions from both libraries can create complex pre-processor conflicts.
With all of this being said, it is highly recommended that stdio be ignored altogether unless one finds themselves in absolute need, which would be a rare occurrence in and of itself.