C Programming Language

What is C?

The C programming language is a general-purpose, procedural language that supports structured programming and provides low-level access to the system memory. It provides a straightforward, consistent, powerful interface for programming systems. C language is a system programming language because it can be used to do low-level programming (for example driver and kernel). It is generally used to create hardware devices, OS, drivers, kernels, etc. For example, Linux kernel is written in C. It can't be used for internet programming like Java, .Net, PHP, etc.

USES OF C:

‘C’ language is widely used in embedded systems.
It is used for developing system applications.
It is widely used for developing desktop applications.
Most of the applications by Adobe are developed using ‘C’ programming language.
It is used for developing browsers and their extensions. Google’s Chromium is built using ‘C’ programming language.
It is used to develop databases. MySQL is the most popular database software which is built using ‘C’.
It is used in developing an operating system. Operating systems such as Apple’s OS X, Microsoft’s Windows, and Symbian are developed using ‘C’ language. It is used for developing desktop as well as mobile phone’s operating system.
It is used for compiler production.
It is widely used in IOT applications.

What are the features of C?

Portability
Structured Programming language
Powerful
Rich Standard Library
Libraries Support
Separate Compilation
Middle-Level Language
Syntax Based Language
Format Free Language
Compiled Language
Case sensitive Language

Variables in C

A variable is a name of the memory location. It is used to store data. Its value can be changed, and it can be reused many times. It is a way to represent memory location through symbol so that it can be easily identified.

C Program to accept two numbers from the user and print back the sum on the screen

Write a C program to Accept a number from the user and test whether it is prime or not.

Write a C program to print the first 100 prime numbers.

Write a C program to print all the prime numbers between 2 to 100.

Write a C program to print the first 10 numbers of the fibonacci series.

Dynamic Memory Allocation

Dynamic memory allocation in C is a way of allocating memory for variables or data structures at run time, instead of compile time. This allows the program to use only the amount of memory that is needed, and to free the memory when it is no longer used. Dynamic memory allocation is useful for creating data structures that have variable size or unknown size at compile time, such as linked lists, trees, graphs,etc.

Advantages of Dynamic Memory Allocation

It allows for creating data structures that have variable size or unknown size at compile time, such as linked lists, trees, graphs, etc.
It ensures that only the amount of memory that is needed is used, and that the memory is freed when it is no longer used. This results in more efficient use of resources and can increase performance significantly.
It allows for reusing the memory that is freed by the user, unlike static memory allocation that cannot reuse the unused memory.

Disadvantages of Dynamic Memory Allocation

It is slower than static memory allocation, because the memory address is not known at compile time and the program has to search for a suitable memory block at run time.
It can result in memory leaks if the memory is not freed properly by the user after use. This can cause the program to consume more memory than needed and eventually crash.
It can cause memory fragmentation if the memory is allocated and freed in an irregular pattern. This can reduce the performance of the program and make it difficult to find a contiguous memory block for large allocations.

What is Structure?

A structure in C is a user-defined data type that can be used to group items of possibly different types into a single type. The struct keyword is used to define the structure in the C programming language. The items in the structure are called its members and they can be of any valid data type.

Advantages of Structures

They allow us to create heterogeneous collections of data items, which can represent complex entities such as students, employees, products, etc. For example, we can store the roll number, name, marks and address of a student in a single structure variable.
They reduce the complexity of handling multiple variables for each record. For example, instead of using five integer variables, five string variables and five float variables to store the details of five students, we can use an array of five structure variables.
They increase the productivity of the programmer by eliminating the burden of dealing with records that contain heterogeneous data items.
They enhance the code readability and maintainability by using a single name to represent complex records.
They are suitable for some mathematical operations that involve complex numbers, distances, times, etc. For example, we can use structures to add two complex numbers or two distances in a feet-inch system.

What is a Pointer?

A pointer in C is a variable that can store the address of another variable or a memory location. We can use pointers to access and modify the data stored in that memory location. Pointers are very useful for low-level programming, dynamic memory allocation, and creating complex data structures.

Advantages of Pointers

Pointers can be used to dynamically allocate memory at run time using functions like `malloc` and `free`. This allows us to create data structures of variable size and complexity, such as linked lists, trees, graphs, etc.
Pointers can be used to pass arguments to functions by reference, instead of by value. This means that the function can modify the original variable in the caller's scope, instead of creating a copy of it. This can improve the performance and efficiency of the program, as well as avoid unnecessary memory allocation and copying.
Pointers can be used to return multiple values from a function, by passing pointers to variables that will store the results. For example, a function that calculates the quotient and remainder of two integers can return both values using pointers, instead of returning a single value or a structure.
Pointers can be used to implement generic functions that can operate on different types of data, by using void pointers. Void pointers are pointers that have no associated data type, and can point to any type of data. By casting void pointers to the appropriate type, we can write functions that can accept and process different types of arguments, such as sorting, searching, copying, etc.
Pointers can be used to create arrays of pointers, which can store the addresses of other variables or arrays. This can be useful for creating multidimensional arrays, jagged arrays, or arrays of strings. Arrays of pointers can also be passed to functions as arguments, allowing us to manipulate complex data structures with ease.

Function in C

A function in C is a block of code that performs a specific task and can be called by other parts of the program. Functions are useful for organizing and reusing code, as well as improving readability and maintainability.

User-defined Function

User-defined function is a type of function that is created by the user to perform a specific task. User-defined functions are useful for organizing and reusing code, as well as improving readability and maintainability. User-defined functions are different from built-in functions, which are predefined by the C language and can be used without any declaration or definition.

Example

C Program to find the greatest among 5 numbers, using a user defined function called Max().

Recursive Function

Recursive function is a function that calls itself either directly or indirectly until a certain condition is met. Recursive functions are useful for solving problems that can be divided into smaller subproblems of the same kind, such as factorial, Fibonacci, tree traversal, etc.

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