# 2.5 Functions and pointers  (Page 10/11)

 Page 10 / 11

The value of a is 7

The value of *aPtr is 7

Notice that the address of a and the value of aPtr are identical in the output, confirming that the address of a is assigned to the pointer variable aPtr.

## Calling functions by reference with pointer arguments

In C++, programmers can use pointers and the dereference operator to simulate call-by-reference. When calling a function with arguments should be modified, the addresses of the arguments are passed. This is normally achieved by applying the address-of operator (&) to the name of the variable whose value will be used. A function receiving an address as an argument must define a pointer parameter to receive the address.

Example

`// Cube a variable using call-by-reference`

`// with a pointer argument`

`#include<iostream.h>`

`void cubeByReference( int * ); // prototype`

`int main()`

`{`

`int number = 5;`

`cout<<"The original value of number is "<<number;`

`cubeByReference(&number );`

`cout<<"\nThe new value of number is "<<number<<endl;`

`return 0;`

`}`

`void cubeByReference( int *nPtr )`

`{`

`*nPtr = (*nPtr) * (*nPtr) * (*nPtr); // cube number in main`

`}`

The output of the above propgram:

The original value of number is 5

The new value of number is 125

## Pointers and arrays

Notice that the name of an array by itself is equivalent to the base address of that array. That is, the name z in isolation is equivalent to the expression&z[0].

Example

`#include<iostream.h>`

`int main()`

`{`

`int z[] = { 1, 2, 3, 4, 5};`

`cout<<“The value return by ‘z’ itself is`

`the addr “<<z<<endl;`

`cout<<“The address of the 0th element of`

`z is “<<&z[0]<<endl;`

`return 0;`

`}`

The output of the above program:

The value return by ‘z’ itself is the addr 0x0065FDF4

The address of the 0th element of z is 0x0065FDF4

Accessing Array Element Using Pointer and Offset

Now, let us store the address of array element 0 in a pointer. Then using the indirection operator, *, we can use the address in the pointer to access each array element.

For example, if we store the address of grade[0] into a pointer named gPtr, then the expression *gPtr refers to grade[0].

One unique feature of pointers is that offset may be included in pointer expression.

For example, the expression *(gPtr + 3) refers to the variable that is three (elements) beyond the variable pointed to by gPtr.

The number 3 in the pointer expression is an offset. So gPtr + 3 points to the element grade[3] of the grade array.

Example

`#include<iostream.h>`

`int main()`

`{`

`int b[] = { 10, 20, 30, 40 }, i, offset;`

`int *bPtr = b; // set bPtr to point to array b`

`cout<<"Array b printed with:\n"`

`<<"Array subscript notation\n";`

`for ( i = 0; i<4; i++ )`

`cout<<"b["<<i<<"] = "<<b[ i ]<<'\n';`

`cout<<"\nPointer/offset notation\n";`

`for ( offset = 0; offset<4; offset++ )`

`cout<<"*(bPtr + "<<offset<<") = "`

`<<*( bPtr + offset )<<'\n';`

`return 0;`

`}`

The output of the above program is:

Array b printed with:

Array subscript notation

b[0] = 10

b[1] = 20

b[2] = 30

b[3] = 40

Pointer/offset notation

*(bPtr + 0) = 10

*(bPtr + 1) = 20

*(bPtr + 2) = 30

*(bPtr + 3) = 40

## Pointers and strings

In C++ we often use character arrays to represent strings. A string is an array of characters ending in a null character (‘\0’). Therefore, we can scan through a string by using a pointer. Thus, in C++, it is appropriate to say that a string is a constant pointer – a pointer to the string’s first character.

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
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