The pow() function returns base raised to the expth power. There's a domain error if base is zero and exp is less than or equal to zero. There's also a domain error if base is negative and exp is not an integer. There's a range error if an overflow occurs.

The function malloc() returns a pointer to a chunk of memory of size size, or NULL if there is an error. The memory pointed to will be on the heap, not the stack, so make sure to free it when you are done with it.

The free() function deallocates the space pointed to by ptr, freeing it up for future use. ptr must have been used in a previous call to malloc(), calloc(), or realloc().

The exit() function stops the program. exit_code is passed on to be the return value of the program, where usually zero indicates success and non-zero indicates an error.

The calloc() function returns a pointer to space for an array of num objects, each of size size. The newly allocated memory is initialized to zero.

The atoi() function converts str into an integer, and returns that integer. str should start with some sort of number, and atoi() will stop reading from str as soon as a non-numerical character has been read.

The function abort() terminates the current program. Depending on the implementation, the return value can indicate failure.

The function fabs() returns the absolute value of arg.

The function rand() returns a pseudorandom integer between zero and RAND_MAX.

The function fputc() writes the given character ch to the given output stream. The return value is the character, unless there is an error, in which case the return value is EOF.

The putchar() function writes ch to STDOUT.

The function ungetc() puts the character ch back in stream.

The realloc() function changes the size of the object pointed to by ptr to the given size. size can be any size, larger or smaller than the original. The return value is a pointer to the new space, or NULL if there is an error.