C is definitely one of the most popular programming languages out there, and it is also one of the easiest. But that doesn’t mean that there aren’t things that people can find out to be quite troublesome. C was designed to be as close to the machine as possible, without being dependent on a particular architecture. It was initially designed by Dennis Ritchie to reimplement the UNIX operating system and as such works quite closely to the underlying machine. You can check out best C tutorials on Hackr.io to learn C programming. Learning C is smooth journey, however, there are a few things that are quite difficult to master in C Language.
Let us look at the topics that cause a problem for most students and try to understand what these are.
1. Arrangement of Data in Memory
Memory alignment refers to the arrangement of data in memory. It deals with the issue of accessing the data and dealing with them as units of information available from the main memory. It needs to be understood that the main memory is a contiguous block of memory, each having a fixed number of bits. The location of the address can access the data which is represented by this fixed number of bits. Thus these addresses are the smallest units of memory that can be manipulated by the user through his program. In C, the programmer has to deal with functions like memse_16aligned and posix_memalign. Most people do not understand the entire concept.
2. Function Pointers
Another confusing thing in C is the concept of function pointers. It is possible in C to define and use function pointers, i.e., the pointer variable can be created that point to functions. These function pointers can be declared, and values can be assigned to them in the form of functions. They can then be used to access the functions they point to. Most students get confused about how these functions are invoked and used. Even their declaration often becomes an issue. Though most people tend to skip it, the library function of C recommends using them.
3. Pointer Arithmetic
Many people cannot even distinguish between a pointer to a constant value and a constant pointer, let alone understand the concepts related to pointer arithmetic. Many people try not to mess up with pointers and try to leave them out altogether. That is why people often find it easier not to use pointers at all and instead use just the variables. But this is not possible at all times. Many programmers who use C are unaware of keywords like restrict. Many even do not understand the use of void pointers even after using C for years.
4. Buffer Overflow
Programmers also find it confusing to understand the concept of the buffers. Many do not understand how gets() is different from getline(). Also, the concepts of flushing input and output streams seem complicated to most people who work in C. There is also the confusion between getchar_unclocked and getchar. Many people are used to writing programs without even considering that there could see a possibility of buffer outflow. All this shows how things can get confusing in C.
5. Variable number of Arguments
Most of the C programmers do not get how a variable number of arguments can be passed through a function. This is referred to as a form of polymorphism in languages that support an object-oriented paradigm. Even though people can see how popular functions like the printf and scanf take a varying number of arguments, people cannot implement the same in their code. This shows how simple things can get pretty complicated in C.
6. Cache Effects
Programmers also do not understand the cache effect in C language. A particular piece of code might be slower than the other because of cache stores contiguous values. Since C lies so close to the underlying machine, it has a significant impact on the programs that are run. The effect of cache becomes even more pronounced in algorithms that involve matrices or linear algebra. There are libraries like CBLAS that leverage cache effectively.
7. Memory Management Tricks
Memory management is one of the biggest issues that programmers probably face in C. There needs to the constant care taken about the memory leaks and the dynamic allocation. The difference between malloc, calloc, and realloc needs to be understood as well. Most programmers find it difficult to use these functions and create programs that run smoothly on all systems.
8. Goto and Label
Most people do not use statements like goto and label. These features can be used with a lot of effect in different situations. People avoid it because the incorrect usage often leads to bugs. It is not a big thing to worry about though. Many advanced programmers consider this breaking of flow, not a good technique and ask people to avoid using it.
9. Macros and Preprocessor
These are some of the coolest things that can be found in the C language. But the problem is that most people do not understand how to use them and cannot even write proper syntaxes for them. If a function can be converted into a macro, it will reduce the running time by a large margin. There are pre-processor directives that can be used anywhere within the file. Not only that, there are nested directives as well. This helps to prevent header files from being included multiple times. There is also the option to define and use environmental variables (or constants) that can optimize certain bits of code.
There are lots of other things that needs mention as well. One of these is the range of values in the switch case. Ignoring inputs in scanf is also another thing that most people have not even heard of. There are also lots of small details in C that people have overlooked somewhere along the way and could play an important role in various pieces of code. Another thing that should be mentioned is the undefined behavior in C that students often do not know about. Many people thus misinterpret how the operations work. The sequence point is one of those topics in C that get encountered rarely and cannot be easily understood. There are undefined behaviors of C that depend on the underlying architecture.