C is a general-purpose, procedural programming language that has been influential in the development of many modern programming languages. Designed to be efficient and flexible, it is commonly used for system programming, developing operating systems, and creating application software. C provides low-level access to memory and allows bit manipulation, making it a preferred choice for writing performance-critical software.
C was developed in the early 1970s by Dennis Ritchie at Bell Labs as an evolution of the B language, which was influenced by BCPL and ALGOL. Originally, it was intended for system programming on the Unix operating system, which also originated at Bell Labs. The language's design focused on providing a high-level abstraction over assembly language while retaining the efficiency of low-level programming.
By the late 1970s, C gained widespread adoption in the programming community, and the publication of "The C Programming Language" by Brian Kernighan and Dennis Ritchie in 1978 significantly contributed to its popularity. The first standardized version, called C89 or ANSI C, was adopted by the American National Standards Institute (ANSI) in 1989. The International Organization for Standardization (ISO) later adopted it, resulting in ISO C99 in 1999, which introduced several new features such as inline functions and variable-length arrays. The most recent major standard, C11, was published in 2011, and C18, a bug fix release, followed in 2018.
C remains one of the most widely used programming languages in the world, especially in systems programming, embedded systems, and high-performance applications. Its syntax and concepts have influenced many other languages, including C++, C#, Java, and Objective-C. Its ongoing relevance can be seen in operating systems (Linux, Windows), network programming, embedded systems, and various high-performance computing tasks.
C allows direct manipulation of memory through pointers. For example:
int x = 10;
int *p = &x; // Pointer p holds the address of x
C supports structured programming through functions, enabling code modularity. A simple function definition looks like this:
void greet() {
printf("Hello, World!\n");
}
C includes various control flow structures like if, switch, for, while, and do-while, which facilitate decision-making.
if (x > 0) {
printf("Positive number\n");
}
C has several built-in data types: int, char, float, double, etc. It also supports user-defined data types using structures.
struct Point {
int x;
int y;
};
C includes a rich set of libraries for input/output operations, string manipulation, and mathematical computations.
#include <stdio.h>
#include <math.h>
double sqrtValue = sqrt(16);
C allows explicit type casting, which is useful for converting between types.
double pi = 3.14;
int intPi = (int)pi; // intPi will be 3
C supports enumerated types for creating custom types.
enum Color { RED, GREEN, BLUE };
C includes preprocessor directives like #define, #include, which handle code before compilation.
#define PI 3.14
C allows variable declarations within a specific scope, enhancing encapsulation.
{
int temp = 5; // temp is only valid within this block
}
C does not support function overloading like C++, but it allows for default arguments via manual implementation.
int add(int a, int b) {
return a + b;
}
C requires a compiler to transform source code into machine code. The most popular compilers include GCC (GNU Compiler Collection), Clang, and MSVC (Microsoft Visual C++).
To compile a C program, you can typically use a command like:
gcc -o myprogram myprogram.c
This compiles myprogram.c into an executable named myprogram.
Several IDEs support C programming, such as:
These IDEs provide features like syntax highlighting, debugging tools, and project management.
C is used extensively in various domains, including:
C is often compared to several other programming languages, as it shares similarities and serves as a foundation for many:
C can be translated into languages that support procedural programming constructs and low-level optimizations easily. When translating C code to a higher-level language, developers should pay attention to memory management differences, as higher-level languages often feature garbage collection.
Several source-to-source translation tools can help convert C code to other languages, including: