GATE CSE 2000 | Question: 1.16

Question

Aliasing in the context of programming languages refers to

• A. multiple variables having the same memory location
• B. multiple variables having the same value
• C. multiple variables having the same identifier
• D. multiple uses of the same variable

Comments

Option A.

https://en.wikipedia.org/wiki/Aliasing_(computing)

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A

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So Lets take an example of aliasing :

int a = 10 ;

int *p = &a ;

int *q = &a ;

Now pointers p and q are referencing to the same object a .

Hence a is aliased , in simple terms it means that the memory location of a can be accessed using different names p and q .

Answer 1

Option is A.

In computer programming, aliasing refers to the situation where the same memory location can be accessed using different names. For instance, if a function takes two pointers A and B which have the same value, then the name A aliases the name B.

Comments

In sql aliasing means temporarily rename a table.same concept in c ?

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@MRINMOY_HALDER

is sql a programming language as mentioned in the question?

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Bhartendu Kumar

there is no programing language mentioned in the question.

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For instance, if a function takes two pointers A and B which have the same value, then the name A aliases the name B.

Can you give a code snippet for the above statement as it will make it more clear .

Answer 2

B)multiple variables having the same value

int a=24;
int b=24;
int c=24;

 C)multiple variables having the same identifier

int a=23;
char a='A';

D)multiple uses of the same variable

int a=23;
 a=a*a;

A)multiple variables having the same memory location

int a=20;
int *p=&a;

This example also good http://www.cs.uregina.ca/Links/class-info/cplusplus/Standards/Disk10/aliasing_c.html

Comments

@Soumya

actually variable and identifier refers to same in C programming

right?

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you are right.

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@srestha the link that you have given, in there, there is the stmt. “ /* call SomeFunction with the Global Variable as a parameter */ ”. how can a global variable be defined inside the main function? Is it a typo?

Answer 3

A OPTION

Comments

Call by reference is the best example for that.

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we can relate to SQL query also...

SQL aliases are used to give a table, or a column in a table, a temporary name.

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C Programming Language does not allow call by reference.

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@akash.dinkar12

is sql a programming language as mentioned in the question? SQL (Structured Query Language) is a database management language for relational databases. SQL itself is not a programming language.

Though for argument's shake one may include it as programming language which maybe valid, but the spirit of the question is against it.

Answer 4

int i=10;
int *p=&i;
As long as p points to i,  we say that *p is an alias for i.

Comments

You sure? Because if i has a memory location 100 then p will point to i but p can have a different memory location, say 200.

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@Sambhrant Maurya

yes and for Option A to be true by this argument, variables here are

1. i

2. p

only. And clearly,

" multiple variables having the same memory location " (option A)

is not the case here. Though the, memory location

&i can be accessed by two ways :
&i and *p.

Logic of UNION gives OPTION A. Not this argument