|
|
 Handling
of
Character Strings
A
string is
a collection of characters. In terms of programming, it can be
defined as an array of characters. Any group of characters (except
double quote sign) defined between double quote marks is a constant
string. For example, if the following string
"Sachin
is
a
good programmer."
has
to be displayed on the screen, then we will give
printf("\"Sachin
is a
good
programmer.\"");
in
the program. The \" is to print the double quote itself onto the
screen.
The
common operations related to character strings are:
String
variables are declared similar to any other array variables in C. For
example if we want to declare a string variable str of
a maximum size of 8 characters, then it can be done as follows
char
str[8];
When
the compiler assigns a character string to a character array, it
automatically supplies a null character ('\0')
at the end of the string. So
the size of string should be such that it can hold the entire string
plus one null character.
In
order to avoid the confusion we can give initializations without
specifying the array size. For example:
char
str[] = {'S','A','C','Y','\0'}
This
will define a string of five elements.
Reading
strings from terminal
The
function scanf with the %s format allows us to read a word input by the
user, the same way as integers , real values & characters
are read using %d, %f & %c respectively.
For
example
char
name[10];
scanf("%s",name);
Dissimilar
to the integer , float & characters the %s format doesnt require the
ampersand before the variable
name. The main problem is, that the scanf
stops reading a string of characters when it encounters the first
white space. So if we give for above example
Sachin
Mehta
Then
the scanf statement will read only Sachin into the variable name.
In
many text processing applications, we need to read an entire line of
text. In that case as we can't use scanf statement, we can always use
the getchar funtion to read the entire line or word
as
follows
char
line[80],ch;
int
c = 0;
do
{
ch
= getchar();
line[c] = ch;
c++;
}while(ch != '\n');
c = c-1;
line[c]
= '\0';
Writing
strings to screen
We
have seen how we can use printf statement to directly output the string
within double quotes to the screen. Now we will see the outputting of
strings using string variables. For example the contents of the variable
name can be printed as
printf("%s",name);
We
also have something called the precision with which
the string variable has to printed out.
For
example
printf("%7.3s",name)
This
specifies that only the first 3 characters have to be printed in a total
field width of 7 characters &
right justified in the allocated width by default. We can include
a minus sign to make it left justified(%-7.3).
The
following points should be noted
-
When
the field width is less than the length of the string, the entire
string is printed.
-
The
integer value on the right side of the decimal point specifies the
number of characters to be printed.
-
When
the number of characters to be printed is specified as zero, nothing
is printed.
-
The
minus sign in the specification causes the string to be printed
left-justified.
We
will see
rest of the topics related to strings in the next article.
– Sachin Mehta
March 30, 2001
C/C ++
Managing
Input-Output Operations
Managing
Output Operations
Decision
Making And Branching
Decision Making and Branching (if
statement)
Decision
Making and Looping
The
Do Statement
Arrays
Arrays
- Multi-Dimensional
Handling
of Character Strings
Handling of Character Strings - 2
User Defined Functions
User Defined Functions...contd
Handling of Functions
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