History and charitaristics of C

README.md

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-# ctut
+# C Musings
+
+Some musings on C-family languages, by Nora for Ania!
+
+## History of the C Family
+
+In the early days of computing, MIT, General Electric, and Bell Labs created MULITCS,
+the Multiplexed Information and Computing Service. This operating system introduced
+many ideas that are commonplace today. It also kind of sucked, and the project fell apart.
+
+From the ashes rose UNIX, an operating system which, like all OSes at the time, was written
+entirely in non-portable assembly code for a specific machine, the DEC PDP-10. It used
+an interpreted language called B for some non-performance-critical code that needed to be
+easy to modify.
+
+As it became popular in the early 1970s, Dennis Ritchie, Brian Kernighan, and others decided
+to port it to a number of other computers. To ease this task, they invented a computer language
+that abstracted over the specifics of machine language of any particular computer, but was
+close enough to the model exposed by most machines that, with a little machine-specific
+assembly code, the only thing that had to be ported to each new machine was the compiler.
+
+The compiler is a "simple" piece of code that translates the C code to machine-specific
+instructions. Nowadays, compilers are extremely complex, as they perform optimization as
+well as simple compilation.
+
+Because C is so low level, it is entirely _imperative_. All of its high-level features,
+such as structures and function pointers, come from the way the machine works, not from
+any magic (runtime) applied by the compiler.
+
+### C++
+
+C++ is an invention of Bjarne Stroustroup, a brilliant computer scientist who decided to
+apply object oriented principles to C. The result was an absolute mess of a language
+that is nonetheless very powerful and, as time goes on, is becoming more and more safe
+and easy to use.
+
+It has somewhat more of a runtime then C, and the compiler does a lot more work, including
+permitting type-system level templating.
+
+### C#
+
+C# is Microsoft's answer to Java. It's really similar to Java and has very little to do
+with C.
+
+## The C Programming Language
+
+That's the name of a [terrible book](https://www.amazon.com/Programming-Language-2nd-Brian-Kernighan/dp/0131103628)
+that you shouldn't read. I did, it blew my mind and I learned nothing.
+
+Anyway, what defines the C language?
+
+C is **statically typed**. That means, like Java and unlike Python, a variable has to
+keep the same type throughout the program:
+
+```c
+int a = 24;
+a = "Hello, world!"; // Compiler error
+```
+
+C is **weakly typed**. That means, unlike both Java and Python, C will do it's _very best_
+to do _something_ even when you give it types that make little sense, _based on the way
+the PDP-10 would have done it in its CPU_.
+
+```c
+int a = 25;
+char b = 'b';
+a + b; // This is an integer of the value 25 plus the integer value of the letter b.
+```
+
+C is **procedural**. Its primary abstraction is the procedure call, or function call.
+This is as opposed to object-oriented languages, for example.
+
+Finally, C is **memory unsafe**. Because it has no runtime and gives you access to the
+very lowest level of the machine (or at least does a good job of pretending), you can
+do silly things without anyone stopping you.
+
+```c
+char[] c = "Hello, world!"; // A string is an array of characters.
+char nonsense = c[134]; // This will cause a problem, probably.
+```
+
+This code won't throw an `IndexOutOfBounds` exception or anything; there's no runtime
+to check that. Instead, the compiler will very earnestly try to write code that does this;
+it will get the address of the start of the array `c`, compute the memory address 134 bytes
+later, and try to see what's there. This will certainly be gibberish and might cause the
+operating system to kill your program.
 
-A C tutorial.