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Character classification functions
Category Functions
Letters isalpha( )
Lowercase letters islower( )
Uppercase letters isupper( )
Decimal digits isdigit( )
Hexadecimal digits isxdigit( )
Letters and decimal digits isalnum( )
Printable characters (including whitespace) isprint( )
Printable, non-whitespace characters isgraph( )
Whitespace characters isspace( )
Whitespace characters that separate words in a line of text isblank( )
Punctuation marks ispunct( )
Control characters iscntrl( )

The functions isgraph() and iswgraph() behave differently if the execution character set contains other byte-coded, printable, whitespace characters (that is, whitespace characters which are not control characters) in addition to the space character (' '). In that case, iswgraph() returns false for all such printable whitespace characters, while isgraph() returns false only for the space character (' ').

Case mapping functions

The functions listed in [link] yield the uppercase letter that corresponds to a given lowercase letter, and vice versa. All other argument values are returned unchanged.

Character conversion functions
Conversion Functions in ctype.h
Upper- to lowercase tolower( )
Lower- to uppercase toupper( )

String processing functions

A string is a continuous sequence of characters terminated by '\0', the string terminator character. The length of a string is considered to be the number of characters before the string terminator. 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 .

C does not have a basic type for strings, and hence has no operators to concatenate, compare, or assign values to strings. Instead, the standard library provides numerous functions, listed in

[link] to perform these and other operations with strings. The header string.h declares the functions for conventional strings of char. The names of these functions begin with str.

Like any other array, a string that occurs in an expression is implicitly converted into a pointer to its first element. Thus when you pass a string as an argument to a function, the function receives only a pointer to the first character, and can determine the length of the string only by the position of the string terminator character.

String-processing functions
Purpose Functions
Find the length of a string. strlen( )
Copy a string. strcpy( ), strncpy( )
Concatenate strings. strcat( ), strncat( )
Compare strings. strcmp( ), strncmp( ), strcoll( )
Transform a string so that a comparison of two transformed strings using strcmp( ) yields the same result as a comparison of the original strings using the locale-sensitive function strcoll( ). strxfrm( )
In a string, find:
- The first or last occurrence of a given character strchr( ), strrchr( )
- The first occurrence of another string strstr( )
- The first occurrence of any of a given set of characters strcspn( ), strpbrk( )
- The first character that is not a member of a given set strspn( )
Parse a string into tokens strtok( )
#include<stdio.h>#include<conio.h>#include<string.h>// You must declare the library string.h // to use functions strcpy, strcmp...void main() {char str1[10] = “abc”;char str2[10] = “def”;clrscr(); printf(“ str1: %s”,str1);printf(“\n str2: %s”,str2); printf(“\n strcmp(str1,str2) = %d”,strcmp(str1,str2));printf(“\n strcat(str1,str2) = %s”,strcat(str1,str2)); printf(“\n str1: %s”,str1);printf(“\n str2: %s”,str2); printf(“\n strcpy(str1,str2) = %s”,strcpy(str1,str2));printf(“\n str1: %s”,str1); printf(“\n str2: %s”,str2);strcpy(str1,”ab”); strcpy(str2,”abc”);printf(“\n strcmp(str1,str2) = %d”,strcmp(str1,str2)); getch();}
Got questions? Get instant answers now!

here is the sample session with the above program

str1: abc str2: defstrcmp(str1,str2) = -3 strcat(str1,str2) = abcdefstr1: abcdef str2: defstrcpy(str1,str2) = def str1: defstr2: def strcmp(str1,str2) = -3

Questions & Answers

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
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket 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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