![]() For example, suppose you have a float that contains the weight of something, and you want to display it. The major difference between printf() and Serial.print() is that, before passing the things you want to write, you must tell printf() the type of those things. printf() is the equivalent of Arduino’s Serial.print(). ![]() If you’ve done any C programming, you probably used the printf() function, which writes things to the terminal. Everything you can do with the String class, you can also do with a C string, even if it’s usually more complicated. Indeed, the String class is just a fancy wrapper on top of a C string. Keep this picture in mind because every time you write a string literal, this is exactly what goes in memory, whether you use the String class or not. The picture below shows how the bytes of the string “hello” are laid out in RAM. We call this last byte the “terminator” because it marks the end of the sequence. In C, a string is a contiguous sequence of characters ended by a 0. As you probably know, we can use any C feature in C++, and that what we’re going to do in this article: we’ll formats strings as C programmers do.įirst, let’s look at how the C language models strings. So how can we get rid of the String class? We’ll take some distance with C++ for a moment and get back to plain old C. Use several String instances in your program, and soon, the RAM is full of holes like Swiss cheese. The problem with the String class is that it forces you to use the heap and allocates blocks of variables size. To prevent fragmentation, you should always allocate blocks of the same size, or better, don’t use the heap at all. String url = String ( "" ) + user + "/repos?page=" + page What’s the problem with the String class?īut why should we avoid the String class? As I explained in a previous article, heap fragmentation is a major concern in embedded programming.
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