Library Functions Questions and Answers

Answer: B

The correct matching is a-iii, b-iv, c-ii, d-i.

• acos(d), the inverse cosine, is declared in math.h (iii).
• abs(i), the integer absolute value, is declared in stdlib.h (iv).
• fprintf(f, ...), printed as fprint, writes formatted output to a file stream and is in stdio.h (ii).
• time(p) is declared in time.h (i).

A common slip is to look for abs in math.h, which holds fabs for floating-point values; the integer abs lives in stdlib.h, which rules out the codes giving it math.h.

Answer: A

Correct answer: tanh(double x)

A function call or declaration needs the argument in parentheses: tanh(double x). tanh is the hyperbolic tangent, declared in <math.h> as double tanh(double).

Answer: A

string.h is the header in the C standard library for the C programming language which contains macro definitions, constants, and declarations of functions and types used not only for string handling but also various memory handling functions.

Answer: B

Correct answer: True

The statement as phrased - that the limits.h macros appear nowhere else - is true: CHAR_BIT, INT_MAX and their relatives are defined only in <limits.h>, and the floating-point limits only in <float.h>. Names such as NULL and size_t are the ones that appear in several headers.

Answer: A

Correct answer: 1

If srand is never called, rand behaves as though srand(1) had been - the initial seed is 1. That is why an unseeded program produces the same sequence every time it runs.

Answer: C

Correct answer: jmp_buf

jmp_buf is an array type declared in <setjmp.h>, holding the calling environment - registers, stack pointer, program counter - saved by setjmp. Being an array is what lets it be passed to longjmp without an explicit &.

Answer: C

Correct answer: returns a random number generator with a random value based on time

randomize() seeds the random number generator from the system clock, so that a program produces a different sequence on each run. Without it, rand() starts from the same seed every time and repeats the same numbers - which is convenient for debugging and useless for a game.

Answer: C

Correct answer: atof()

atof() parses a string into a double, atoi() into an int and atol() into a long. strtok() is unrelated, splitting a string into tokens on a set of delimiters.

Answer: A

Correct answer: True

ftell(fp) returns the current position as a long - the byte offset from the start for a binary file. Its usual companion is fseek: save a position with ftell, read on, and return to it later.

Answer: A

Correct answer: ULONG_MIN

There is no ULONG_MIN, and there could be no use for one: the minimum of an unsigned type is always 0, so the standard defines only the maxima for unsigned types. Signed types get both, hence LONG_MIN and LONG_MAX.