Header files in C contain declarations for functions, variables, and macros that are defined in other source files. They are used for code organization, reusability, and to provide necessary information about the functions and data types used in a program.

File pointers in C are used to keep track of the current position in a file during input and output operations. They are essential for reading and writing data at specific positions within a file, moving the file pointer, and managing file operations efficiently.

The 'assert' macro is used for debugging in C. It checks a specified condition during program execution, and if the condition is false, it triggers an assertion failure, helping identify bugs and unexpected behavior.

'rand' is used to generate a random integer between 0 and 'RAND_MAX'. 'srand' is used to seed the random number generator. By providing a seed value to 'srand', you can ensure that the sequence of random numbers generated is different each time the program runs.