91. What is meant by file opening?
Ans: The action of connecting a program to a file is called opening of a file. This requires creating
an I/O stream before reading or writing the data.
92. What is a file pointer?
Ans: The pointer to a FILE data type is called as a stream pointer or a file pointer. A file pointer points to the block of information of the stream that had just been opened.
93How is a file closed ?
Ans: A file is closed using fclose() function
Eg. fclose(fp);
Where fp is a file pointer.
94. What is a random access file?
Ans: A file can be accessed at random using fseek() function
fseek(fp,position,origin);
fp file pointer
position number of bytes offset from origin
origin 0,1 or 2 denote the beginning ,current position or end of file respectively.
Ans: The action of connecting a program to a file is called opening of a file. This requires creating
an I/O stream before reading or writing the data.
92. What is a file pointer?
Ans: The pointer to a FILE data type is called as a stream pointer or a file pointer. A file pointer points to the block of information of the stream that had just been opened.
93How is a file closed ?
Ans: A file is closed using fclose() function
Eg. fclose(fp);
Where fp is a file pointer.
94. What is a random access file?
Ans: A file can be accessed at random using fseek() function
fseek(fp,position,origin);
fp file pointer
position number of bytes offset from origin
origin 0,1 or 2 denote the beginning ,current position or end of file respectively.
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95. What is the purpose of ftell ?
Ans: The function ftell() is used to get the current file represented by the file pointer.
ftell(fp);
returns a long integer value representing the current file position of the file pointed by the
file pointer fp.If an error occurs ,-1 is returned.
96. What is the purpose of rewind() ?
Ans: The function rewind is used to bring the file pointer to the beginning of the file.
Rewind(fp);
Where fp is a file pointer.Also we can get the same effect by
feek(fp,0,0);
Ans: The function ftell() is used to get the current file represented by the file pointer.
ftell(fp);
returns a long integer value representing the current file position of the file pointed by the
file pointer fp.If an error occurs ,-1 is returned.
96. What is the purpose of rewind() ?
Ans: The function rewind is used to bring the file pointer to the beginning of the file.
Rewind(fp);
Where fp is a file pointer.Also we can get the same effect by
feek(fp,0,0);
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97. Difference between a array name and a pointer variable?
Ans: A pointer variable is a variable where as an array name is a fixed address and is not a
variable. A
pointer variable must be initialized but an array name cannot be initialized. An array name being a constant value , ++ and — operators cannot be applied to it.
98. Is the allocated space within a function automatically deallocated when the function returns?
Ans: No pointer is different from what it points to .Local variables including local pointers
variables in a function are deallocated automatically when function returns.,But in case of a
local pointer variable ,deallocation means that the pointer is deallocated and not the block of
memory allocated to it. Memory dynamically allocated always persists until the allocation is freed
or the program terminates.
99. What are the advantages of using array of pointers to string instead of an array of strings?
Ans:
i) Efficient use of memory.
ii) Easier to exchange the strings by moving their pointers while sorting.
100. What would be the equivalent pointer expression foe referring the same element as
a[p][q][r][s] ?
Ans : *( * ( * ( * (a+p) + q ) + r ) + s)
Ans: A pointer variable is a variable where as an array name is a fixed address and is not a
variable. A
pointer variable must be initialized but an array name cannot be initialized. An array name being a constant value , ++ and — operators cannot be applied to it.
98. Is the allocated space within a function automatically deallocated when the function returns?
Ans: No pointer is different from what it points to .Local variables including local pointers
variables in a function are deallocated automatically when function returns.,But in case of a
local pointer variable ,deallocation means that the pointer is deallocated and not the block of
memory allocated to it. Memory dynamically allocated always persists until the allocation is freed
or the program terminates.
99. What are the advantages of using array of pointers to string instead of an array of strings?
Ans:
i) Efficient use of memory.
ii) Easier to exchange the strings by moving their pointers while sorting.
100. What would be the equivalent pointer expression foe referring the same element as
a[p][q][r][s] ?
Ans : *( * ( * ( * (a+p) + q ) + r ) + s)
