Whereas in some programming languages it doesn't matter if you use single or double quotes, it matters highly in C++ (and some others, such as Java, also). For example, if you're a webdeveloper and write a function in JavaScript, you can even mix them and it will still work and give you the right output (as long as you don't use single ones at the beginning and doubles at the end of the same string).

While in Java, for example, you get an error if you want to run a function which contains a variable that hasn't been initialized  java: variable x might not have been initialized , not so in C++ and that can be tricky.

In C++ variables which haven't been initialized get random values which can or will almost always lead to unexpected results.