Lecture notes
Computer system
- Module
- C programme (BETCH)
- Institution
- PEARSON (PEARSON)
Computer system, computer science, computer skills, computer language
[Show more]
Seller
Follow
Content preview
Difference between Structure and UnionStructure Union
For defining structure use
1 For defining union we use union keyword
struct keyword.
Structure occupies more
2 Union occupies less memory space than Structure.
memory space than union.
In Structure we can access
3 all members of structure at a In union we can access only one member of union at a time.
time.
Structure allocates separate Union allocates one common storage space for its all
4 storage space for its every members. Union find which member need more memory
members. than other member, then it allocate that much space
Bit‐Fields
Syntax
struct {
type [member_name] : width ;
};
The following table describes the variable elements of a bit field −
Elements Description
type An integer type that determines how a bit-field's value is interpreted.
The type may be int, signed int, or unsigned int.
member_name The name of the bit-field.
width The number of bits in the bit-field. The width must be less than or equal
to the bit width of the specified type.
C PROGRAMMING Page 261
,The variables defined with a predefined width are called bit fields. A bit field can hold more
than a single bit; for example, if you need a variable to store a value from 0 to 7, then you can
define a bit field with a width of 3 bits as follows −
struct {
unsigned int age : 3;
} Age;
The above structure definition instructs the C compiler that the age variable is going to use only
3 bits to store the value. If you try to use more than 3 bits, then it will not allow you to do so. Let
us try the following example –
#include <stdio.h>
#include <string.h>
struct {
unsigned int age : 3;
} Age;
int main( ) {
Age.age = 4;
printf( "Sizeof( Age ) : %d\n", sizeof(Age) );
printf( "Age.age : %d\n", Age.age );
Age.age = 7;
printf( "Age.age : %d\n", Age.age );
Age.age = 8;
printf( "Age.age : %d\n", Age.age );
return 0;
}
Output
Sizeof( Age ) : 4
C PROGRAMMING Page 262
, Age.age : 4
Age.age : 7
Age.age : 0
typedef
The typedef is a keyword that allows the programmer to create a new data type name for an
existing data type. So, the purpose of typedef is to redefine the name of an existing variable type.
Syntax
typedef datatype alias_name;
Example of typedef
#include<stdio.h>
#include<conio.h>
typedef int Intdata; // Intdata is alias name of int
void main()
{
int a=10;
Integerdata b=20;
typedef Intdata Integerdata; // Integerdata is again alias name of Intdata
Integerdata s;
clrscr();
s=a+b;
printf("\n Sum:= %d",s);
getch();
}
Output
Sum: 20
C PROGRAMMING Page 263
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller akhilagouri. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £15.79. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
52355 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now