C Standard Library

Question 1

What is the C address of operator used for in the scanf() function

Answer 1

To allow the scanf function to store the input in a variable

Question 2

What is the return value of the C printf() function

Answer 2

The number of characters it printed

Question 3

C Function: strlen()

Answer 3

strlen() give the length of the string passed to it

Question 4

How do you read a string from the keyboard using the C scanf() function

Answer 4

Call the function with the format string containing a %s specifier and the character array you want to save the string in but don’t use the &. for example: scanf(“ %s”, array_name);

Question 5

What is the return value of the C scanf() function

Answer 5

The number of characters it successfully read

Question 6

C Function: strcpy(string1, string2)

Answer 6

strcpy() copies the contents of string2 into string1

Question 7

C Function: strcat(string1, string2)

Answer 7

strcat() concatenates the contents of string2 onto the end of string1

Question 8

C Function: strcmp(string1, string2)

Answer 8

strcmp() compares string1 and string2 and returns 0 if string1 is the same as string2 or a non-zero value if they are both different

Question 9

C Function: fgets()

Answer 9

fgets() reads a string from the keyboard

Question 10

What is the general form of the C fgets() function

Answer 10

fgets(name, sizeof(name), stdin);

Question 11

What is the first argument in an C fgets() function call

Answer 11

The name of the character array in which to save the contents of the string

Question 12

What is the second argument in an C fgets function call

Answer 12

An integer that indicates the maximum number of characters to read, usually the size of the variable itself using the sizeof operator

Question 13

What is the third argument in an C fgets function call

Answer 13

The file from which to read, usually stdin

Question 14

C Function: isdigit()

Answer 14

isdigit() evaluates the number passed to it and if it is a decimal digit returns true and false otherwise

Question 15

C Function: system()

Answer 15

system() allows your programs to call commands to the system

Question 16

C Function: islower()

Answer 16

islower() evaluates the character passed to it and if it is a lowercase letter returns true and false otherwise

Question 17

C Function: isupper()

Answer 17

isupper() evaluates the character passed to it and if it is an uppercase letter returns true and false otherwise

Question 18

C Function: tolower()

Answer 18

tolower() converts the character passed to it to a lowercase letter

Question 19

C Function: toupper()

Answer 19

toupper() converts the character passed to it to an uppercase letter

Question 20

C Function: exp(x)

Answer 20

exp() returns the value of x to the power of x

Question 21

C Function: pow(x, y)

Answer 21

pow() returns x raised to the power to y

Question 22

C Function: sqrt()

Answer 22

sqrt() computes the square root of the number passed to it

Question 23

C Function: log()

Answer 23

log() returns the natural logarithm (base e) of the number passed to it

Question 24

C Function: log10()

Answer 24

log10() returns the logarithm (base 10) of the number passed to it

Question 25

C Function: fabs()

Answer 25

fabs() returns the absolute value of the number passed to it

Question 26

C Function: ciel(x)

Answer 26

ciel() rounds x to the smallest integer not less than x

Question 27

C Function: floor(x)

Answer 27

floor() rounds x to the largest integer not greater than x

Question 28

C Function: fmod(x, y)

Answer 28

fmod() returns the remainder of x/y as a floating-point number

Question 29

C Function: sin(x)

Answer 29

sin() returns the trigonometric sine of x in radians

Question 30

C Function: cos(x)

Answer 30

cos() returns the trigonometric cosine of x in radians

Question 31

C Function: tan(x)

Answer 31

tan() return the trigonometric tangent of x in radians

Question 32

C Function: isalnum()

Answer 32

isalnum() returns true if the character passed to it is an uppercase, lowercase letter, or a decimal digit and false otherwise

Question 33

C Function: ispunct()

Answer 33

ispunct() returns true if the character passed to it is a printing character that isspace() and isalnum() return false

Question 34

C Function: isspace()

Answer 34

isspace() returns true if the character passed to it is a whitespace character (space, '\n', 't', 'v', 'r', 'f')

Question 35

C Function: isblank()

Answer 35

isblank() returns true if the character passed to it is a standard blank character (space, 't')

Question 36

C Function: iscntrl()

Answer 36

iscntrl() returns true if the character passed to it is a control character

Question 37

C Function: isgraph()

Answer 37

isgraph() returns true if the character passed to it is any printing character excluding space

Question 38

C Function: isprint()

Answer 38

isprint() returns true if the character passed to it is any printing character including space

Question 39

C Function: isxdigit()

Answer 39

isxdigit() returns true if the character passed to it is a hexadecimal digit

Question 40

C Function: isalpha()

Answer 40

isalpha() returns true if the character passed to it is an uppercase or lowercase letter

Question 41

C Function: fflush()

Answer 41

fflush() clears the contents of an input or an output buffer

Question 42

C Function: scanf()

Answer 42

scanf() obtains input typed in from the keyboard

Question 43

C Function: printf()

Answer 43

printf() is used to print formatted output

Question 44

C Function: rand()

Answer 44

rand() generates a whole number from 0 to a library-defined number

Question 45

C Function: srand()

Answer 45

srand() tells the rand() function to produce a true random number every time it is executed

Question 46

C Function: time()

Answer 46

time() returns the current time in seconds

Question 47

How do you obtain values in a certain range when using the C rand() function

Answer 47

from 0 to integer: rand() % integer and from 1 to integer: 1 + rand() % integer

Question 48

C Header: stdbool.h

Answer 48

stdbool.h makes it easier to work with boolean values

Question 49

C Header: assert.h

Answer 49

assert.h includes macros and information for adding diagnostics that aid program debugging

Question 50

C Header: ctype.h

Answer 50

ctype.h includes function prototypes for functions that test characters for certain properties, and function prototypes for functions that can be used to convert lowercase letters to uppercase letters and vice versa

Question 51

C Header: errno.h

Answer 51

errno.h includes macros that are useful for reporting error conditions

Question 52

C Header: float.h

Answer 52

float.h includes the floating-point size limits of the system

Question 53

C Header: limits.h

Answer 53

limits.h includes the integral size limits of the system

Question 54

C Header: locale.h

Answer 54

locale.h includes function prototypes and other information that enables a program to be modified for the current locale on which it’s running

Question 55

C Header: setjmp.h

Answer 55

setjmp.h includes function prototypes for functions that allow bypassing of the usual function call and return sequence

Question 56

C Header: signal.h

Answer 56

signal.h includes function prototypes and macros to handle various conditions that may arise during program execution

Question 57

C Header: stdarg.h

Answer 57

stdarg.h includes macros for dealing with a list of arguments to a function whose number and types are unknown

Question 58

C Header: stddef.h

Answer 58

stddef.h includes common type definitions used by C for performing calculations

Question 59

C Header: stdlib.h

Answer 59

stdlib.h includes function prototypes for conversions of numbers to text and text to numbers, memory allocation, random numbers, and other utility functions

Question 60

C Header: time.h

Answer 60

time.h includes function prototypes and types for manipulating the time and date

Question 61

C Haeder: string.h

Answer 61

string.h includes function prototypes for string-processing functions

Question 62

C Header: stdio.h

Answer 62

stdio.h contains functions for standard input/output

Question 63

C Header: math.h

Answer 63

math.h contains mathematical functions