61. Differentiate between for loop and a while loop? What are it uses?
Ans: For executing a set of statements fixed number of times we use for loop while when the number of iterations to be performed is not known in advance we use while loop.
62. What is storage class? What are the different storage classes in C?
Ans: Storage class is an attribute that changes the behavior of a variable. It controls the lifetime, scope and linkage. The storage classes in c are auto, register, and extern, static, typedef.
Ans: For executing a set of statements fixed number of times we use for loop while when the number of iterations to be performed is not known in advance we use while loop.
62. What is storage class? What are the different storage classes in C?
Ans: Storage class is an attribute that changes the behavior of a variable. It controls the lifetime, scope and linkage. The storage classes in c are auto, register, and extern, static, typedef.
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63. What the advantages of using Unions?
Ans: When the C compiler is allocating memory for unions it will always reserve enough room for the largest member.
64. What is a far pointer? Where we use it?
Ans: In large data model (compact, large, huge) the address B0008000 is acceptable because in these model all pointers to data are 32bits long. If we use small data model(tiny, small, medium) the above address won’t work since in these model each pointer is 16bits long. If we are working in a small data model and want to access the address B0008000 then we use far pointer. Far pointer is always treated as a 32bit pointer and contains a segment address and offset address both of 16bits each. Thus the address is represented using segment : offset format B000h:8000h. For any given memory address there are many possible far address segment : offset pair. The segment register contains the address where the segment begins and offset register contains the offset of data/code from where segment begins.
Ans: When the C compiler is allocating memory for unions it will always reserve enough room for the largest member.
64. What is a far pointer? Where we use it?
Ans: In large data model (compact, large, huge) the address B0008000 is acceptable because in these model all pointers to data are 32bits long. If we use small data model(tiny, small, medium) the above address won’t work since in these model each pointer is 16bits long. If we are working in a small data model and want to access the address B0008000 then we use far pointer. Far pointer is always treated as a 32bit pointer and contains a segment address and offset address both of 16bits each. Thus the address is represented using segment : offset format B000h:8000h. For any given memory address there are many possible far address segment : offset pair. The segment register contains the address where the segment begins and offset register contains the offset of data/code from where segment begins.
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65. What is a normalized pointer, how do we normalize a pointer?
Ans: It is a 32bit pointer, which has as much of its value in the segment register as possible. Since a segment can start every 16bytes so the offset will have a value from 0 to F. for normalization convert the address into 20bit address then use the 16bit for segment address and 4bit for the offset address. Given a pointer 500D: 9407,we convert it to a 20bitabsolute address 549D7,Which then normalized to 549D:0007.
66. What is a NULL Pointer? Whether it is same as an uninitialized pointer?
Ans: Null pointer is a pointer which points to nothing but uninitialized pointer may point to anywhere.
67. Are pointers integer?
Ans: No, pointers are not integers. A pointer is an address. It is a positive number.
68. What does the error ‘Null Pointer Assignment’ means and what causes this error?
Ans: As null pointer points to nothing so accessing a uninitialized pointer or invalid location may cause an error.
69. Are the expressions arr and &arr same for an array of integers?
Ans: Yes for array of integers they are same.
70. How pointer variables are initialized? (IMP)
Ans: Pointer variables are initialized by one of the following ways.
I. Static memory allocation
II. Dynamic memory allocation
Ans: It is a 32bit pointer, which has as much of its value in the segment register as possible. Since a segment can start every 16bytes so the offset will have a value from 0 to F. for normalization convert the address into 20bit address then use the 16bit for segment address and 4bit for the offset address. Given a pointer 500D: 9407,we convert it to a 20bitabsolute address 549D7,Which then normalized to 549D:0007.
66. What is a NULL Pointer? Whether it is same as an uninitialized pointer?
Ans: Null pointer is a pointer which points to nothing but uninitialized pointer may point to anywhere.
67. Are pointers integer?
Ans: No, pointers are not integers. A pointer is an address. It is a positive number.
68. What does the error ‘Null Pointer Assignment’ means and what causes this error?
Ans: As null pointer points to nothing so accessing a uninitialized pointer or invalid location may cause an error.
69. Are the expressions arr and &arr same for an array of integers?
Ans: Yes for array of integers they are same.
70. How pointer variables are initialized? (IMP)
Ans: Pointer variables are initialized by one of the following ways.
I. Static memory allocation
II. Dynamic memory allocation
