The other answerers are correct with regard to the C programming language. They seem to be mistaken about C++ though.
First up, C++ was originally called C with Classes. Classes is so you can code in Object Oriented ways. But, C++ does not make you code in Object Oriented. Most of C has been kept, so you can program however you want in C++. When I say this, they are two other types of programming. Functional and procedural. These two are an olders tyle of programming.
In C++ you can program in the three different types and your programs can have all three different types at the same time.
Trying not to confuse you, there is a language called Java. Now Java is Object Oriented. You have to program in Object Oriented for Java. You are ont limited to programming in Object Oriented in C++, but you can if you want.
Secondly, C++ is the most widely used language for programming games. SO if you want to program games, you need to know C++.
I would find a good book for programming in C++. There is a book called "Beginning C++ Through Game Programming Second Edition". The ISBN for this book is 978-1-59863-360-3
You can use the ISBN to order the book through a book shop.
http://www.cengage.com/cengage/student.do?codeid=Z530&sortby=copy&type=all_radio&courseid=CDD10&product_isbn=9781598633603&disciplinenumber=215&codeFlag=true
How difficult is it to learn?
That all depends on you as a person. Some people can do it quickly and eaily, and others can find it hard and difficult. This is the same with all things. People are more suited to learning different things.
But if you really want to learn, you will learn. It make take longer than you think, but if you are committed, you should be able to learn it.
Good luck, and happy programming.