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The control flow of a language specify the order in which operations are performed. Each program includes many statements. Statements are processed one after another in sequence, except where such control statements result in jumps.

Statements and blocks

An expression such as x = 0 or i++ or printf(. . . .) becomes a statement when it is followed by a semicolon, as in

x=0; i++;printf(. . . .);

In the C language, the semicolon is a statement terminator.

A block also called a compound statement, or compound statement, lets you group any number of data definitions, declarations, and statements into one statement. All definitions, declarations, and statements enclosed within a single set of braces are treated as a single statement. You can use a block wherever a single statement is allowed.

In blocks, declarations and definitions can appear anywhere, mixed in with other code. Note that there is no semicolon after the right brace that ends a block.

{ into I = 0; /* Declarations */ static long a;extern long max;++a; /* Statements */ if( a>= max) { . . . } /* A nested block */. . . }
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An expression statement is an expression followed by a semicolon. The syntax is:

[expression] ;

The expression—an assignment or function call, for example—is evaluated for its side effects. The type and value of the expression are discarded.

A statement consisting only of a semicolon is called an empty statement, and does not perform any operation. For Example

for ( i = 0; str[i] != '\0'; ++i ); // Empty statement

If, if else statements

The if statement has two forms:

if(expression) statement

and

if(expression) statement1 else statement2

In the first form, if (and only if) the expression is non-zero, the statement is executed. If the expression is zero, the statement is ignored. Remember that the statement can be compound; that is the way to put several statements under the control of a single if.

The second form is like the first except that if the statement shown as statement1 is selected then statement2 will not be, and vice versa.

Here are the flowcharts of the two forms of if statement

The form involving else works the same way, so we can also write this.

if(expression) if(expression)statement elsestatement

this is now ambiguous. It is not clear, except as indicated by the indentation, which of the ifs is responsible for the else. If we follow the rules that the previous example suggests, then the second if is followed by a statement, and is therefore itself a statement, so the else belongs to the first if.

That is not the way that C views it. The rule is that an else belongs to the first if above that hasn't already got an else. In the example we're discussing, the else goes with the second if.

To prevent any unwanted association between an else and an if just above it, the if can be hidden away by using a compound statement, here it is.

if(expression){ if(expression)statement }elsestatement

if(expression){

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
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
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
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
Brian Reply
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?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
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 ?
Bob Reply
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?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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Source:  OpenStax, Introduction to computer science. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10776/1.1
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