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Basic of strings

A string is a continuous sequence of characters terminated by '\0', the null character. The length of a string is considered to be the number of characters excluding the terminating null character. There is no string type in C, and consequently there are no operators that accept strings as operands.

Instead, strings are stored in arrays whose elements have the type char or wchar_t. Strings of wide characters that is, characters of the type wchar_tare also called wide strings . The C standard library provides numerous functions to perform basic operations on strings, such as comparing, copying, and concatenating them.

Declarations and uses of strings

You can initialize arrays of char or wchar_t using string literals. For example, the following two array definitions are equivalent:

char str1[30] = "Let's go"; // String length: 8; array length: 30.char str1[30] = { 'L', 'e', 't', '\'', 's',' ', 'g', 'o', '\0' };

An array holding a string must always be at least one element longer than the string length to accommodate the terminating null character. Thus the array str1 can store strings up to a maximum length of 29. It would be a mistake to define the array with length 8 rather than 30, because then it wouldn't contain the terminating null character.

If you define a character array without an explicit length and initialize it with a string literal, the array created is one element longer than the string length. An Example

char str2[ ] = " to London!";// String length: 11 (note leading space);// array length: 12.

The following statement uses the standard function strcat() to append the string in str2 to the string in str1. The array str1 must be large enough to hold all the characters in the concatenated string.

#include<string.h>char str1[30] = "Let's go";char str2[ ] = " to London!";/* ... */ strcat( str1, str2 );puts( str1 );

The output printed by the puts() call is the new content of the array str1:

Let's go to London!

The names str1 and str2 are pointers to the first character of the string stored in each array. Such a pointer is called a pointer to a string , or a string pointer for short. String manipulation functions such as strcat() and puts() receive the beginning addresses of strings as their arguments. Such functions generally process a string character by character until they reach the terminator, '\0'. The function in is one possible implementation of the standard function strcat() . It uses pointers to step through the strings referenced by its arguments.

Built-in functions for character and string processing

Character processing functions

The standard library provides a number of functions to classify characters and to perform conversions on them. The header ctype.h declares such functions for byte characters, with character codes from 0 to 255.

The results of these functions, except for isdigit() and isxdigit() , depends on the current locale setting for the locale category LC_CTYPE. You can query or change the locale using the setlocale() function.

Character classification functions

The functions listed in [link] test whether a character belongs to a certain category. Their return value is nonzero, or true, if the argument is a character code in the given category.

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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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