stdlib.h

The `#include ` directive includes the standard library header file in your C program. The `stdlib.h` header provides functions, macros, and types for various general-purpose tasks in C. Here are some commonly used functions provided by `stdlib.h`: 1. Memory Management: - `malloc()`: Allocates a block of memory. - `calloc()`: Allocates and initializes a block of memory. - `realloc()`: Changes the size of a previously allocated block of memory. - `free()`: Deallocates a block of memory. 2. String Conversion and Pseudo-Random Numbers: - `atoi()`: Converts a string to an integer. - `atof()`: Converts a string to a floating-point number. - `rand()`: Generates a pseudo-random integer. - `srand()`: Seeds the random number generator. 3. Process and Environment Control: - `system()`: Executes a shell command. - `exit()`: Terminates the program execution. - `getenv()`: Retrieves the value of an environment variable. 4. Sorting and Searching: - `qsort()`: Sorts an array using a user-defined comparison function. - `bsearch()`: Searches for a key in a sorted array using a user-defined comparison function. 5. Dynamic Memory Allocation Control: - `atexit()`: Registers a function to be called at program termination. - `abort()`: Aborts the program execution. 6. Integer Arithmetic: - `abs()`: Computes the absolute value of an integer. - `labs()`: Computes the absolute value of a long integer. 7. String Manipulation: - `itoa()`: Converts an integer to a string. - `system()`: Executes a shell command. These are just a few examples of the functions provided by `stdlib.h`. The header file also includes additional macros, constants, and types for general-purpose tasks. When you include `stdlib.h` in your program, you gain access to these functions and can utilize them for memory management, string manipulation, process control, and more.

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