The C Language
The legend and horror that is the C language
The C programming language is a general-purpose programming language created by Dennis Ritchie in the 1970s at Bell Labs. It became highly influential, particularly in the development of operating systems (notably UNIX), device drivers, kernels, and more. C has also inspired the creation of many modern programming languages, such as Python, C++ (C with classes), and Java.
C is widely used in various computing environments, ranging from supercomputers to microcontrollers and embedded systems. Its ability to directly manipulate hardware and memory makes it an essential language in low-level programming, where control over system resources is critical.
C is a compiled language, meaning you need to compile the code (using GCC, for example) into machine-readable code. This process creates an executable file, which you can then run to execute the provided code.
Sources:
Learn-c
geeksforgeeks
w3schools
Below are some key topics you need to understand to grasp the power of C and how it can be used to create complex, efficient, and high-performance software.
Basic Syntax and Structure
Headers
Programs written in C rely on headers to access essential functions, such as scanf and printf. Without this, you wouldn’t be able to use these built-in functions and would need to write your own versions to replicate their functionality and performance.
// #include is a preprocessor directive
// <stdio.h> is the header itself
#include <stdio.h>
Writing these functions yourself is not recommended, as they have already been thoroughly developed and tested for efficiency and reliability.
To name a few <stdio.h>,<stlib.h>, and <math.h> *are part of the C Standard Library, so you don't need to write your own implementation for them.
Function Naming Scheme
Every C program must have a main function, which serves as the entry point for the program. This is where the execution begins, and the code you write is placed inside this function.
The int keyword specifies the return type of the main function, indicating that it returns an integer value once the program finishes running. A return value of 0 typically means the program ran successfully, while any non-zero value indicates an error or unsuccessful execution.
Every function in C needs a name, and in this case, main is the function's name (think of it as an identifier). The main function is special because it's where execution starts, but it can also be called by other functions in the program, like this: main() (don’t worry, we’ll discuss this in more detail when we cover functions).
//** simple main function**
// int - return type
// main - function name
int main () {
}
//**A more advanced adaptation of main to read command line arguments.**//
// int - return type
// main - function name
// int argc - number of command line arguments passed
/* char* argv[] - stores the command line arguments as strings
in the argv array with each command stored in its own array index*/
int main (int argc, char* argv[]) {
}
int argc and char* argv[] parameters allow for direct storage and retrival of command line arguments instead of storing and accessing them indirectly.
You can name other functions anything you like, but main is required so the compiler knows where to begin execution.
Return Types
The main function contains a return type int and we now need to include another keyword return. return is how you would exit the function and return something to the caller (which is our operating system in this case) with its associated type (which in our case is an int so we return a integer value).
/*assuming the header and main function have been well defined and each return type has an
associated function with said return type*/
return 0; -> returns an integer value to the caller
return 3.41; -> returns a float/double value to the caller
return arr; -> returns a string to the caller // assuming arr has been well defined
return 'a'; -> returns a character value to the caller
It is important to note that if the return type is not void you cannot return nothing (denotate as return)