Góc học tập
16/01/2021 10:50:14 PM

Câu hỏi trắc nghiệm ngôn ngữ lập trình C (tiếp theo)

Q91:

Which one of the following is valid for opening a read-only ASCII file?

 Choice 1
fileOpen (filenm, "r");
Choice 2
fileOpen (filenm, "ra");
Choice 3
fileOpen (filenm, "read");
Choice 4
fopen (filenm, "read");
Choice 5
fopen (filenm, "r");[Ans]

Q92:
f = fopen( filename, "r" );
Referring to the code above, what is the proper definition for the variable f?
Choice 1
FILE f;
Choice 2
FILE *f;[Ans]
Choice 3
int f;
Choice 4
struct FILE f;

Choice 5
char *f;

Q93:
If there is a need to see output as soon as possible, what function will force the output from the buffer into the output stream?
Choice 1
flush()
Choice 2
output()
Choice 3
fflush()
Choice 4
dump()
Choice 5
write()

Q94:
short int x; /* assume x is 16 bits in size */
What is the maximum number that can be printed using printf("%d\n", x), assuming that x is initialized as shown above?
Choice 1
127
Choice 2
128
Choice 3
255
Choice 4
32,767 [Ans]
Choice 5
65,536

Q95:

Code:

 

void crash (void)

{

 printf("got here");

 *((char *) 0) = 0;

} 


The function crash(), defined above, triggers a fault in the memory management hardware for many architectures. Which one of the following explains why "got here" may NOT be printed before the crash?
Choice 1
The C standard says that dereferencing a null pointer causes undefined behavior. This may explain why printf() apparently fails.
Choice 2
If the standard output stream is buffered, the library buffers may not be flushed before the crash occurs.
Choice 3
printf() always buffers output until a newline character appears in the buffer. Since no newline was present in the format string, nothing is printed.
Choice 4
There is insufficient information to determine why the output fails to appear. A broader context is required.
Choice 5
printf() expects more than a single argument. Since only one argument is given, the crash may actually occur inside printf(), which explains why the string is not printed. puts() should be used instead.

Q96:

Code:

 

char * dwarves [] = {

  "Sleepy",

  "Dopey" "Doc",

  "Happy",

  "Grumpy" "Sneezy",

  "Bashful",

}; 


How many elements does the array dwarves (declared above) contain? Assume the C compiler employed strictly complies with the requirements of Standard C.
Choice 1
4
Choice 2
5[Ans]
Choice 3
6
Choice 4
7
Choice 5
8

Q97:
Which one of the following can be used to test arrays of primitive quantities for strict equality under Standard C?
Choice 1
qsort()
Choice 2
bcmp()
Choice 3
memcmp()
Choice 4
strxfrm()
Choice 5
bsearch()

Q98:

Code:

 

int debug (const char * fmt, ...) {

  extern FILE * logfile;

  va_list args;

  assert(fmt);

  args = va_arg(fmt, va_list);

  return vfprintf(logfile, fmt, args);

} 


The function debug(), defined above, contains an error. Which one of the following describes it?
Choice 1
The ellipsis is a throwback from K&R C. In accordance with Standard C, the declaration of args should be moved into the parameter list, and the K&R C macro va_arg() should be deleted from the code.
Choice 2
vfprintf() does not conform to ISO 9899: 1990, and may not be portable.
Choice 3
Library routines that accept argument lists cause a fault on receipt of an empty list. The argument list must be validated with va_null() before invoking vfprintf().
Choice 4
The argument list args has been improperly initialized. Choice 5
Variadic functions are discontinued by Standard C; they are legacy constructs from K&R C, and no longer compile under modern compilers.

Q99:

Code:

 

char *buffer = "0123456789";

char *ptr = buffer;

ptr += 5;

printf( "%s\n", ptr );

printf( "%s\n", buffer ); 


What will be printed when the sample code above is executed?
Choice 1
0123456789
56789
Choice 2
5123456789
5123456789
Choice 3
56789
56789
Choice 4
0123456789
0123456789
Choice 5
56789
0123456789 [Ans]

Q100:
/* Get the rightmost path element of a Unix path. */

Code:

 

char * get_rightmost (const char * d)

{

 char rightmost [MAXPATHLEN];

 const char * p = d;

 assert(d != NULL);

 while (*d != '\0')

 {

  if (*d == '/')

   p = (*(d + 1) != '\0') ? d + 1 : p;

  d++;

 }

 memset(rightmost, 0, sizeof(rightmost));

 memcpy(rightmost, p, strlen(p) + 1);

 return rightmost;

} 


The function get_rightmost(), defined above, contains an error. Which one of the following describes it?
Choice 1
The calls to memset() and memcpy() illegally perform a pointer conversion on rightmost without an appropriate cast.
Choice 2
The code does not correctly handle the situation where a directory separator '/' is the final character.
Choice 3
The if condition contains an incorrectly terminated character literal.
Choice 4
memcpy() cannot be used safely to copy string data.
Choice 5
The return value of get_rightmost() will be invalid in the caller's context.

 

NGUYỄN THỊ BẢO TRANG