C

Question 1

What are C programs are compiled into?

Answer 1

Object code.

Question 2

What is gcc?

Answer 2

The GNU Compiler Collection is an open source C compiler.

Question 3

What is the default executable name produced by gcc?

Answer 3

a.out

Question 4

How can you specify the executable name produced by gcc?

Answer 4

Using the -o switch.

Question 5

What does cpp stand for?

Answer 5

cpp is the C preprocessor.

Question 6

When does cpp examine source code, relative to compilation?

Answer 6

Source code is examined by cpp prior to compilation.

Question 7

cpp must be called separately from gcc.

Answer 7

False, gcc calls cpp automatically.

Question 8

What does the following line do?
cpp hello.c

Answer 8

By default, independent invocations of cpp prints the rewritten source code to the screen.

Question 9

How are cpp directives distinguished from regular C code?

Answer 9

A leading # symbol.

Question 10

Macros are pure textual substitutions, typically used for defining what 2 things?

Answer 10

Constants, and very simple functions in compact form.

Question 11

What would occur if gcc encountered a #include directive?

Answer 11

It would produce an invalid error syntax.

Question 12

In what way are standard header files included differently than user defined header files?

Answer 12

Using <file>, instead of “path”.

Question 13

Why is no additional path information included with standard header file names?

Answer 13

Because these are located in pre-defined folders that cpp and the compiler will always search.

Question 14

Can operating systems or platforms define their own standard header files?

Answer 14

Yes.

Question 15

What about the C compilation process makes header files necessary?

Answer 15

C compilation is a line by line process that will generate errors if a not previously defined identifier is encountered.

Question 16

Source files are compiled interdependently.

Answer 16

False, they are compiled independently, which further reinforces the need for header files.

Question 17

Which compiler error is commonly associated with the omission of a header file?

Answer 17

“Symbol could not be resolved.”

Question 18

The C library is big, relative to other languages.

Answer 18

False.

Question 19

%i can be used in place of %d to specify an integer.

Answer 19

True.

Question 20

Which format specifier is used for pointers?

Answer 20

%p

Question 21

What should be used in place of printf() for displaying error/warnings?

Answer 21

fprintf(stderr, message, var_list);

Question 22

Why should fprintf() be used in place of printf() for displaying errors?

Answer 22

Because fprintf() allows specification of output stream, and stderr is unbuffered (usually prints immediately).

Question 23

NULL is a keyword in C.

Answer 23

False - NULL is a macro defined in several standard C headers.

Question 24

How can NULL be defined as a macro?

Answer 24

#define NULL ((void *)0)

Question 25

Are C functions pass by value, reference, or both?

Answer 25

Pass by value.

Question 26

If int *p1 = arr; int *p2 = arr + 4; and and ints are 4 bytes, what does int x = (char*)p2 - (char*)p1 equal?

Answer 26

16

Question 27

Will the following line compile, if p is of type (char*) and stdio.h is included?
printf(p);

Answer 27

Yes, but a warning will be generated.

Question 28

If char *p = “hi”; what does printf(p + 1); do?

Answer 28

Outputs “i” to standard output.

Question 29

Which ASCII character proceeds each string in C?

Answer 29

The null character ‘\0’, which is ASCII value 0. It isn’t printable.

Question 30

If char c = ‘\0’; what does (c == NULL) return?

Answer 30

Compiler issues a warning, as you’d be comparing a character with a pointer.

Question 31

The following is a valid way of obtaining the number of elements in arr:
int arr[] = {1, 2, 3, 4};
int size = sizeof(arr)/sizeof(arr[0]);

Answer 31

True.

Question 32

Where does the following code produce a compile error?
int a = 1;
void *p = (int *)&a;
printf(“%d”, *p);

Answer 32

Line 3, because a void pointer cannot be dereferenced.

Question 33

If p is of type (int *), what’s the difference between the following two bits of code?
++*p
*++p

Answer 33

The first adds 1 to the integer p points to, the second returns the number held by the location adjacent to p.

Question 34

Declare (but don’t initialize) two integer pointers in 1 line.

Answer 34

int *p1, *p2;

Question 35

What does the following print?
int array[5][5];
printf(“%d”, ((array == *array) && (*array == array[0])));

Answer 35

1

Question 36

What’s the difference between big endian and little endian?

Answer 36

In little endian, the least significant value is stored first, whereas in big endian, the most significant value is stored first.

Question 37

Faster access to non-local variables is achieved using an array of pointers to activation records, called a..?

Answer 37

Activation tree.

Question 38

What does the following declare?
int * f[ ] ()

Answer 38

An array of functions returning pointers to integers.

Question 39

A reference can never be NULL.

Answer 39

True.

Question 40

What does the following declare?
int (*f())[ ]

Answer 40

int (*f())[ ] declares a function returning a pointer to an array of integers.