C Arrays
Q. Difference between arrays and linked list?
Ans: An array is a repeated pattern of variables in contiguous storage. A linked list is a set of
structures scattered through memory, held together by pointers in each element that point to the next element. With an array, we can (on most architectures) move from one element to the next by adding a fixed constant to the integer value of the pointer. With a linked list, there is a “next” pointer in each structure which says what element comes next.
Ans: An array is a repeated pattern of variables in contiguous storage. A linked list is a set of
structures scattered through memory, held together by pointers in each element that point to the next element. With an array, we can (on most architectures) move from one element to the next by adding a fixed constant to the integer value of the pointer. With a linked list, there is a “next” pointer in each structure which says what element comes next.
Q. What is pointer to a pointer?
Ans: If a pointer variable points another pointer value. Such a situation is known as a pointer to a pointer.
Example:
int *p1,**p2,v=10;
P1=&v; p2=&p1;
Here p2 is a pointer to a pointer.
Ans: If a pointer variable points another pointer value. Such a situation is known as a pointer to a pointer.
Example:
int *p1,**p2,v=10;
P1=&v; p2=&p1;
Here p2 is a pointer to a pointer.
Q. What is an array of pointers?
Ans: if the elements of an array are addresses, such an array is called an array of pointers.
Ans: if the elements of an array are addresses, such an array is called an array of pointers.
Q. Difference between linker and linkage?
Ans: Linker converts an object code into an executable code by linking together the necessary built in
functions. The form and place of declaration where the variable is declared in a program determine the linkage of variable.
Ans: Linker converts an object code into an executable code by linking together the necessary built in
functions. The form and place of declaration where the variable is declared in a program determine the linkage of variable.
Q. Is it possible to have negative index in an array?
Ans: Yes it is possible to index with negative value provided there are data stored in this location. Even if it is illegal to refer to the elements that are out of array bounds, the compiler will not produce error because C has no check on the bounds of an array.
Ans: Yes it is possible to index with negative value provided there are data stored in this location. Even if it is illegal to refer to the elements that are out of array bounds, the compiler will not produce error because C has no check on the bounds of an array.
Q. Why is it necessary to give the size of an array in an array declaration?
Ans: When an array is declared, the compiler allocates a base address and reserves enough space in memory for all the elements of the array. The size is required to allocate the required space and hence size must be mentioned.
Ans: When an array is declared, the compiler allocates a base address and reserves enough space in memory for all the elements of the array. The size is required to allocate the required space and hence size must be mentioned.
Q. What modular programming?
Ans: If a program is large, it is subdivided into a number of smaller programs that are called modules or subprograms. If a complex problem is solved using more modules, this approach is known as modular programming.
Ans: If a program is large, it is subdivided into a number of smaller programs that are called modules or subprograms. If a complex problem is solved using more modules, this approach is known as modular programming.
Q. What is preincrement and post increment?
Ans: ++n (pre increment) increments n before its value is used in an assignment operation or any
expression containing it. n++ (post increment) does increment after the value of n is used.
Ans: ++n (pre increment) increments n before its value is used in an assignment operation or any
expression containing it. n++ (post increment) does increment after the value of n is used.
Q. Write a program to interchange 2 variables without using the third one.
Ans:
a ^= b; ie a=a^b
b ^= a; ie b=b^a;
a ^= b ie a=a^b;
here the numbers are converted into binary and then xor operation is performed.
You know, you’re just asking “have you seen this overly clever trick that’s not worth applying on
modern architectures and only really applies to integer variables?”
Ans:
a ^= b; ie a=a^b
b ^= a; ie b=b^a;
a ^= b ie a=a^b;
here the numbers are converted into binary and then xor operation is performed.
You know, you’re just asking “have you seen this overly clever trick that’s not worth applying on
modern architectures and only really applies to integer variables?”
Q. What is the maximum combined length of command line arguments including the space between adjacent arguments?
Ans: It depends on the operating system.
Ans: It depends on the operating system.
Q. What is a preprocessor, what are the advantages of preprocessor?
Ans: A preprocessor processes the source code program before it passes through the compiler.
1- a preprocessor involves the readability of program
2- It facilitates easier modification
3- It helps in writing portable programs
4- It enables easier debugging
5- It enables testing a part of program
6- It helps in developing generalized program
Ans: A preprocessor processes the source code program before it passes through the compiler.
1- a preprocessor involves the readability of program
2- It facilitates easier modification
3- It helps in writing portable programs
4- It enables easier debugging
5- It enables testing a part of program
6- It helps in developing generalized program
Q. What are the facilities provided by preprocessor?
Ans:
1-file inclusion
2-substitution facility
3-conditional compilation
Ans:
1-file inclusion
2-substitution facility
3-conditional compilation
Q. What are the two forms of #include directive?
Ans:
1.#include”filename”
2.#include
the first form is used to search the directory that contains the source file.If the search fails in the home directory it searches the implementation defined locations.In the second form ,the preprocessor searches the file only in the implementation defined locations.
Ans:
1.#include”filename”
2.#include
the first form is used to search the directory that contains the source file.If the search fails in the home directory it searches the implementation defined locations.In the second form ,the preprocessor searches the file only in the implementation defined locations.
Q. How would you use the functions randomize() and random()?
Ans:
Randomize() initiates random number generation with a random value.
Random() generates random number between 0 and n-1;
Ans:
Randomize() initiates random number generation with a random value.
Random() generates random number between 0 and n-1;
Q. What do the functions atoi(), itoa() and gcvt() do?
Ans:
atoi() is a macro that converts integer to character.
itoa() It converts an integer to string
gcvt() It converts a floating point number to string
Ans:
atoi() is a macro that converts integer to character.
itoa() It converts an integer to string
gcvt() It converts a floating point number to string
Q 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.
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.
Q. Represent a two-dimensional array using pointer?
Ans:
Address of a[I][j] Value of a[I][j]
&a[I][j]
or
a[I] + j
or
*(a+I) + j
*&a[I][j] or a[I][j]
or
*(a[I] + j )
or
*( * ( a+I) +j )
Ans:
Address of a[I][j] Value of a[I][j]
&a[I][j]
or
a[I] + j
or
*(a+I) + j
*&a[I][j] or a[I][j]
or
*(a[I] + j )
or
*( * ( a+I) +j )
Q. Difference between an array of pointers and a pointer to an array?
Ans:
Array of pointers
1- Declaration is: data_type *array_name[size];
2-Size represents the row size.
3- The space for columns may be dynamically
Pointers to an array
1-Declaration is data_type ( *array_name)[size];
2-Size represents the column size.
Ans:
Array of pointers
1- Declaration is: data_type *array_name[size];
2-Size represents the row size.
3- The space for columns may be dynamically
Pointers to an array
1-Declaration is data_type ( *array_name)[size];
2-Size represents the column size.
Q. Difference between array and pointer?Ans:
Array
1- Array allocates space automatically
2- It cannot be resized
3- It cannot be reassigned
4- sizeof (arrayname) gives the number of bytes occupied by the array.
Pointer
1-Explicitly assigned to point to an allocated space.
2-It can be sized using realloc()
3-pointer can be reassigned.
4-sizeof (p) returns the number of bytes used to store the pointer variable p.
Array
1- Array allocates space automatically
2- It cannot be resized
3- It cannot be reassigned
4- sizeof (arrayname) gives the number of bytes occupied by the array.
Pointer
1-Explicitly assigned to point to an allocated space.
2-It can be sized using realloc()
3-pointer can be reassigned.
4-sizeof (p) returns the number of bytes used to store the pointer variable p.
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