week 2 c programming code

Question 1

what is a string in c#

Answer 1

string of characters is a 1D array of characters

Question 2

how much memory does ASCII store

Answer 2

(1 byte) of each character element is stored in
consecutive memory locations

Question 3

what is string terminated by

Answer 3

String is terminated by the null character ‘\0’ (ASCII value 0)

Question 4

what is the length of the null string

Answer 4

The null string (length zero) is the null character only

Question 5

what is use to take input from user in c#

Answer 5

scanf()

Question 6

what is used to output info to user

Answer 6

printf()

Question 7

what is the format for string in c

Answer 7

%s

Question 8

what is the 4 safe string functions

Answer 8

strcpy()
strcat()
strlen()
strcmp

Question 9

what is strcpy()

Answer 9

copies the string from one destination to another

Question 10

what do you need to make sure that you do in strcpy()

Answer 10

need to allocate memory to the destination where you want to put your string
e.g
char[10] destination; -> where i will put the string in;

Question 11

what does strlen do

Answer 11

gets the length of the string;

Question 12

does strlen take into account the null value

Answer 12

no

Question 13

what does strcat do

Answer 13

concatenates 2 strings together

Question 14

in strcat(str1,str2) which string is modified and which stays the same

Answer 14

str2 stays the same and str1 changes as str2 is appended to teh end of str1

Question 15

what does strcmp do

Answer 15

compares 2 strings and see if they are the same

Question 16

if strcmp conpares 2 strings and finds them to be equal then what does it return

Answer 16

it returns 0

Question 17

if strcmp conpares 2 strings and finds them to not be equal then what does it return

Answer 17

returns the numeric difference between the first
non matching characters
or -1 i need to check

Question 18

what are string problems

Answer 18

Need to ensure that sufficient memory is allocated at run-
time for storing the string - not automatically done by the
compiler

• No checks at run-time (and compile-time), hence common
  source of errors
• Such “buffer overflows” have been exploited to achieve
  execution of code supplied by attackers
• Partial solution is to use “safe” functions

Question 19

what is a partial solution to string problems

Answer 19

• Partial solution is to use “safe” functions

Question 20

what are safe string functions

Answer 20

strcpy() strcmp , strlen , strcat

Question 21

what is wrong with this
strncpy(char *dst, char * src, size_t num)

Answer 21

Copies the first num characters of src to dst. If the end of src
(signaled by a null char) is found before num characters have been
copied, dst is padded with zeros until a total of num characters
have been written to it.

No null-character is implicitly appended at the end of dst if src is
longer than num. Thus, in this case, dst shall not be considered a
null terminated C string

Question 22

what is the definition of a pointer

Answer 22

A pointer is a variable that contains the address of a
variable
pointer is also stored in memory

Question 23

what is the unary operator*

Answer 23

• is also calld indirection or dereferencing operator
  applied to a pointer to accesses the object the pointer points to
  e.g c = 5 , *p = &c , d = p now d = 5

Question 24

what is unary operator &

Answer 24

‘address-of’ operator
points to address of object
p =&c
now p now has address of c so p points to c

Question 25

how to declare a pointer in C#

Answer 25

T *p
T is any data type like int or char

Question 26

does string exists in c#

Answer 26

no string does not exists we use char[] instead