C Programming

Question 1

Object files can only have one function per file.

Answer

true

Question 2

To create a relocatable object library archive from a group of object files, enter the command:

Accepted Answer

ar ras libraryfile.a objectfile(s)

Answer

link library file.a object file(s)

Answer

ranlib library file.a objectfile(s)

Answer

zip -r library file.a objectfile(s)

Question 3

You should put code you expect to reuse in other programs into a header file.

Answer

true

Question 4

Dynamically linked object files have the extension .dll in Linux.

Answer

true

Question 5

If you include code in a header file, it will:

Accepted Answer

be copied redundantly in every object file created from source that includes the header.

Answer

All are correct.

Answer

cause a compile error because code, other than declarations, cannot be in a header file.

Answer

create more compact code because it will compile directly with the source instead of being linked from a library.

Question 6

The GCC command line parameter '-c' tells the compiler to:

Accepted Answer

compile only, without linking any code.

Answer

use C syntax as opposed to C# or C++ syntax.

Answer

copy the source file into the object file.

Answer

compress the code output.

Question 7

Function declarations, global variable declarations, and #define directives are good to include in a library's header file because:

Accepted Answer

All are correct.

Answer

They provide an interface to the library's functions and data

Answer

They prevent you from having to expose private code or write 'getters' and 'setters' for the library code.

Answer

They can then be used by any code that includes the header file.

Question 8

The directive #define PI 3.1415

Accepted Answer

tells the compiler to substitute the string "3.1415" in the source wherever it encounters the string "PI".

Answer

tells the compiler to make the variable PI equal to 3.1415

Answer

tells the compiler to alter all instances of PI in the object code to 3.1415

Answer

tells the compiler to substitute the float number 3.1415 in the source wherever it encounters the string "PI".

Question 9

If a library file containing 10 functions is statically linked at compile time instead of dynamically linked at runtime:

Accepted Answer

the executable will be smaller but the space used at runtime will be the same.

Answer

the statement makes no sense because linking only occurs at compile time.

Answer

it can share the library functions with other programs, saving space.

Answer

the statement makes no sense because linking only occurs at runtime.

Question 10

#include "mycode.h" directs the compiler to search for mycode.h in the current directory first. Depending on implementation, it may also search subdirectories of the current directory and the systems include path.

Answer

true

Question 11

To compile relocatable code, use the gcc flag -fPIC.

Answer

true

Question 12

To prevent a header file mycode.h from being included more than once:

Accepted Answer

#ifndef __mycode_h__
#define __mycode_h__
 ... code goes here
#endif
should be included in the header file

Answer

header files should never include other header files.

Answer

-Imycode.h should be added to the gcc compiler flags.

Answer

#ifndef __mycode_h__
#define __mycode_h__
#include "mycode.h"
#endif
should be included in the source file

Question 13

Declarations:

Accepted Answer

All are correct.

Answer

need not include any initialization.

Answer

must come before declared item can be used.

Answer

can go anywhere in a source or header file (except conditional expressions)

Question 14

To add a table of relocatable object modules to an archive, use the 'ranlib' utility in linux.

Answer

true

Question 15

To lump a set of object files together, use the 'ar' (archive) command. The result is a linkable library.

Answer

true

Question 16

The gcc compiler flag -l followed by a path specifies an additional path for the compiler to search for include files.

Answer

true

Question 17

Constants are usually defined in all capitals using a define directive so they will stand out.

Answer

true

Question 18

The #include directive tells the compiler to insert the contents of the specified file into the file that has the directive at the location where the directive is found.

Answer

true

Question 19

Object files consist of the source code for the function(s) they hold.

Answer

true

Question 20

#include <mycode.h> directs the compiler to search for mycode.h in the current directory first, then in the system's include path.

Answer

true

Question 21

int *numPtr;
int num = 100;
numPtr = num;

Accepted Answer

fails because it tries to point numPtr to the address 100.

Answer

stores the address of num into the location pointed at by numPtr

Answer

causes numPtr to point to num.

Answer

fails because numPtr is never initialized.

Question 22

You can do math on a pointer but you can't store the result back into the pointer variable.

Answer

true

Question 23

unsigned long *varname declares varname to be an unsigned long that is used as a pointer.

Answer

true

Question 24

typedef struct mystruct{ char *name;
                                             char *address; } mystruct;
Adding the structure name before the structure itself means you can use the structure before it was declared.

Answer

true

Question 25

struct mystruct{ char *name;
                             char *address; );
struct mystruct *mycontact = malloc(sizeof(struct mystruct));
*(mycontact).name = "Charles";
When the above code executes,

Accepted Answer

mycontact contains a pointer called name that points to a string, "Charles," stored somewhere on the heap.

Answer

it stores the string "Charles" in the variable name inside mycontact.

Answer

it fails because the last line should have been *(mystruct).mycontact.name = "Charles";

Answer

it fails because name did not specify a size and no memory for it was allocated.

Question 26

&varname can be read as 'address of varname'.

Answer

true

Question 27

struct mystruct{ char *name;
                             char *address; };
struct mystruct *mycontact = malloc(sizeof(struct mystruct));
When the above code executes, it

Accepted Answer

creates a variable called mycontact that points to a structure that contains NULL pointers to name and address.

Answer

fails because malloc does not know how big the name or address fields are.

Answer

creates a variable called mycontact that contains a name and an address.

Answer

creates a variable called mycontact that points a variable called mystruct.

Question 28

int *varptr[] = { 1, 2, 3, 4, 5 );
int x = *(varptr + 2);
The above code sets x to 3.

Answer

true

Question 29

int *numPtr;
int num = 100;
numPtr = &num;

Accepted Answer

causes numPtr to point to num.

Answer

fails because it tries to point numPtr to address 100.

Answer

stores 100 in the address pointed to by numPtr.

Answer

fails because numPtr is never initialized.

Question 30

Assume that pointers are 4 bytes, integers are 2 bytes, characters are 1 byte, and float values take up 4 bytes.
typedef struct { char *name;
                            char *ID[8];
                            int rank;
                            float scores[];
                         } gradesRecord;
gradesRecord *grades = malloc(sizeof(gradesRecord);
How many bytes were allocated by the malloc function?

Accepted Answer

Can't allocate without first allocating name

Answer

22

Answer

Can't tell because no dimension was given for scores array.

Answer

14

Question 31

typedef struct mystruct{ char *name;
                                             char *address; };
Adding typedef to the above declaration means I can now declare "mystruct mycontact" instead of "struct mystruct mycontact".

Answer

true

Question 32

struct mystruct{ char *name;
                             char *address; };
struct mystruct *mycontact = malloc(sizeof(struct mystruct));
mycontact->name = "Charles";
When the above code executes,

Accepted Answer

mycontact contains a pointer called name that now points to the string "Charles" stored somewhere in the heap.

Answer

it fails because you can't store a string literal into a pointer.

Answer

it fails because there was no malloc for name to create space for the string.

Answer

it fails because the last line should read &mycontact->name = "Charles";

Question 33

struct mystruct{ char *name;
                             char *address; };
struct mystruct *mycontact = malloc(sizeof(struct mystruct));
char* tempptr = &(mycontact->name);
*tempptr = "Charles";
When the above code executes, it

Accepted Answer

gets the address of name inside mycontact and then sets its value to point to the string "Charles" stored somewhere on the heap.

Answer

gets the address of mycontact and stores the string "Charles" there.

Answer

fails because we tried to store a string, "Charles", inside a pointer, tempptr.

Answer

gets the address pointed to by name inside mycontact and stores the string "Charles" at that location.

Question 34

unsigned long *varname declares varname to be a pointer to an unsigned long integer.

Answer

true

Question 35

int varptr[] = { 1, 2, 3, 4, 5 };
int x = varptr;
The above code sets x to 1.

Answer

true

Question 36

int *numPtr;
int num = 100;
*numPtr = num;

Accepted Answer

fails because numPtr has not been initialized.

Answer

stores 100 in the location numPtr points to.

Answer

points numPtr to num.

Answer

fails because it tries to point numPtr to address 100.

Question 37

typedef struct { char *name;
                            char *address; } mystruct;
The above typedef declaration means I can now declare "mystruct mycontact" instead of "struct mystruct mycontact".

Answer

true

Question 38

int varptr[] = { 1, 2, 3, 4, 5 };
int x = *varptr;
The above code sets x to 1.

Answer

true

Question 39

The elements in a struct can be any type except a pointer.

Answer

true

Question 40

float *fnum = 3.1415

Accepted Answer

stores 3.1415 at the address where fnum points at.

Answer

is invalide because you cannot assign a number to a pointer

Answer

stores 3.1415 in fnum.

Answer

is not a valid statement because a pointer cannot be a fraction.

Question 41

The debug macros in dbg.h will automatically detect errors in the code and print them out

Answer

true

Question 42

You should always compile your code using the command line switch to include debugging info.

Answer

true

Question 43

kill stops and deletes the program being debugged.

Answer

true

Question 44

clear 157 deletes the instruction at line 157.

Answer

true

Question 45

display sum prints out the value of the variable sum each time the program stops at a breakpoint or watchpoint.

Answer

true

Question 46

Using dbg.h and scattering debug messages through the source code is less efficient than using gdb.

Answer

true

Question 47

continue lets the program run until it hits the next breakpoint or the program ends.

Answer

true

Question 48

watch x*y stops execution of the program if the value x*y changes. x and y must be defined in the program.

Answer

true

Question 49

step causes the program to execute one line at a time, slowly, so you can watch the execution.

Answer

true

Question 50

If a debug macro from dbg.h is triggered, it will print the file and line number of the source code that triggered it.

Answer

true

Question 51

list myprog:15 myprog:27 will display the source code from lines 15–27 from myprog.

Answer

true

Question 52

info watchpoints lists information about the watchpoints that have been set.

Answer

true

Question 53

gdb -args ./myprog 7 9 creates a debug session for the program myprog and passes 7 and 9 to it as arguments.

Answer

true

Question 54

break myprog:sum tells the debugger to stop execution when it reaches the sum function in myprog.

Answer

true

Question 55

next goes to the next instruction. If the next instruction is a function call, then it goes to the first instruction inside the function.

Answer

true

Question 56

print x+5 will print 5 added to the value of x, presuming x is defined in the program being debugged.

Answer

true

Question 57

list myprog:sum displays the source code for the sum function in myprog.

Answer

true

Question 58

-d is the argument to gcc to compile the code in a debuggable state.

Answer

true

Question 59

Bracketing a bug with debug messages or even just print statements can be faster than stepping through the code with debug.

Answer

true

Question 60

info break displays information about the last breakpoint reached.

Answer

true

Question 61

A break statement in a loop will cause the current loop iteration to halt and execution of the next loop iteration to begin.

Answer

true

Question 62

The reserved word else is always associated with the closest if statement unless braces are used to define blocks of statements.

Answer

true

Question 63

Declarations can be placed anywhere in the program.

Answer

true

Question 64

If a condition's value is 0, then the condition is evaluated as true.

Answer

true

C Programming

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