List of Header File in C Language with Examples

Here is a list of some commonly used header files in C along with their full names and a brief description of their functionality:

1. `<stdio.h>` (Standard Input/Output):
   - Full Name: Standard Input/Output Header
   - Description: Contains functions for standard input and output operations, including `printf`, `scanf`, `fgets`, `fopen`, etc.

2. `<stdlib.h>` (Standard Library):
   - Full Name: Standard Library Header
   - Description: Provides general-purpose functions for memory allocation, type conversions, random number generation, sorting, etc. Includes functions like `malloc`, `free`, `atoi`, `qsort`, etc.

3. `<string.h>` (String Operations):
   - Full Name: String Header
   - Description: Contains functions for manipulating strings, including string copying, concatenation, comparison, searching, and tokenization. Includes functions like `strcpy`, `strcat`, `strcmp`, `strlen`, `strtok`, etc.

4. `<math.h>` (Mathematical Functions):
   - Full Name: Math Header
   - Description: Provides mathematical functions for common operations, including square root, trigonometric functions, logarithmic functions, exponential functions, etc. Includes functions like `sqrt`, `sin`, `cos`, `pow`, `log`, etc.

5. `<ctype.h>` (Character Handling):
   - Full Name: Character Handling Header
   - Description: Contains functions for character handling and classification, such as checking whether a character is alphabetic, numeric, uppercase, lowercase, etc. Includes functions like `isalpha`, `isdigit`, `toupper`, `tolower`, etc.

6. `<time.h>` (Time and Date):
   - Full Name: Time and Date Header
   - Description: Provides functions for working with time and date, including getting the current time, converting time formats, calculating time differences, and formatting time strings. Includes functions like `time`, `localtime`, `strftime`, etc.

7. `<stdbool.h>` (Boolean Type):
   - Full Name: Boolean Type Header
   - Description: Defines the Boolean data type and constants (`true` and `false`) for representing logical values.

8. `<stddef.h>` (Standard Definitions):
   - Full Name: Standard Definitions Header
   - Description: Provides definitions for common types and macros, including `NULL`, `size_t`, `ptrdiff_t`, etc.

9. `<limits.h>` (Implementation-Defined Constants):
   - Full Name: Implementation-Defined Constants Header
   - Description: Defines implementation-specific limits and properties of integral types, such as maximum and minimum values of integer types, maximum length of character strings, etc.

10. `<assert.h>` (Program Assertions):
    - Full Name: Program Assertions Header
    - Description: Provides the `assert` macro for inserting assertions into code to verify assumptions and detect logical errors during program execution.

These are just a few examples of commonly used header files in C. There are additional header files available for specific functionalities and libraries. You can refer to the C standard library documentation for a comprehensive list of header files and their respective functions in the C programming language.

 In C programming, header files contain function declarations, definitions, and macro definitions that can be included in your C source code files using the `#include` preprocessor directive. They provide access to various libraries and functionalities in the C language. Here's a list of commonly used header files in C along with some examples:

1. `<stdio.h>` (Standard Input/Output):
   - Provides input and output functions such as `printf`, `scanf`, `fgets`, etc.

   Example:
   ```c
   #include <stdio.h>

   int main() {
       printf("Hello, World!\n");
       return 0;
   }
   ```

2. `<stdlib.h>` (Standard Library):
   - Contains general-purpose functions such as memory allocation, type conversion, sorting, etc.

   Example:
   ```c
   #include <stdlib.h>

   int main() {
       int* ptr = (int*)malloc(sizeof(int));
       *ptr = 42;
       free(ptr);
       return 0;
   }
   ```

3. `<string.h>` (String Operations):
   - Provides functions for manipulating strings, including copying, concatenating, and comparing strings.

   Example:
   ```c
   #include <stdio.h>
   #include <string.h>

   int main() {
       char str1[] = "Hello";
       char str2[] = "World";
       strcat(str1, str2);
       printf("%s\n", str1);
       return 0;
   }
   ```

4. `<math.h>` (Mathematical Functions):
   - Contains mathematical functions like `sqrt`, `sin`, `cos`, `pow`, etc.

   Example:
   ```c
   #include <stdio.h>
   #include <math.h>

   int main() {
       double x = 2.5;
       double y = sqrt(x);
       printf("Square root of %f is %f\n", x, y);
       return 0;
   }
   ```

5. `<ctype.h>` (Character Handling):
   - Provides functions for character handling and classification, such as `isalpha`, `isdigit`, `toupper`, etc.

   Example:
   ```c
   #include <stdio.h>
   #include <ctype.h>

   int main() {
       char ch = 'a';
       if (isalpha(ch)) {
           printf("%c is an alphabet\n", ch);
       }
       return 0;
   }
   ```

6. `<time.h>` (Time and Date):
   - Contains functions for manipulating time and date, such as `time`, `localtime`, `strftime`, etc.

   Example:
   ```c
   #include <stdio.h>
   #include <time.h>

   int main() {
       time_t now = time(NULL);
       struct tm* local = localtime(&now);
       printf("Current time and date: %s", asctime(local));
       return 0;
   }
   ```

These are just a few examples of commonly used header files in C. There are many more header files available in C that provide additional functionalities and libraries for various purposes. You can refer to the C standard library documentation or specific library documentation for more information on header files and their functions.