Strings of C#.Net Interview Questions(28)
1.Define
String?
A)String
is a collection of characters. It is an combination of numericals, characters
and special characters. In C#.Net string acts as a reference type. It can be
conceived by “Using System. String”.
2.
What is the difference between string and String?
A)
No difference.
3.
List the different types of operations of strings?
A)
4.
What are the different forms of string?
A)
Strings can be categorized into number of forms. They are:
Ø Mutable
Ø Immutable
5.
What is Mutable?
A)Mutable
means the objects can be changed.StringBuilder
class belongs to mutable type.
6.
What is Immutable?
A)
Immutable means the objects can’t be changed.String class belongs to immutable type.
7.
Is String belongs to mutable or immutable?
A)String
belongs to immutable.
8.What
is the purpose of StringBuilder?
A)
StringBuilder is a class belongs to mutable type.This class can be used when we
want to modify a string without creating a new object.Using StringBuilder class
it improves the performance when concatenating many strings in an iterations or
in a loop.
9.How
can we Instantiate StringBuilder Class?
A)
StringBuilder objectname=new StringBuilder(“”);
E.G:
StringBuilder ss=new StringBuilder(“Welcome to DotnetInterviewQuestion”);
10.How
can we modify by using StringBuilder class?
A)By
using the following methods we can modify the contents of a stringbuilder.
Ø Append()
Ø AppendFormat()
Ø Insert()
Ø Remove()
Ø Replace()
11.
Can we convert StringBuilder object to a string?
A)
Yes. We can convert StringBuilder object to string.By using ToString() method
we can convert stringbuilder value to string.
E.G: StringBuilder sb=new
StringBuilder(“I Love”);
sb.Append(“My Country”);
Console.WriteLine(sb.ToString());
12.What
is the difference between Convert.toString and .ToString()?
A)
Syntax:Convert.ToString(variablename);
Variablename.ToString();
Primary
difference between Convert.toString and .ToString() is Convert.ToString()
method handles null values but .ToString() method it won’t allows null values it throws an null
reference exception error.Good programming practices suggests
Convert.ToString() instead of .ToString().
13.
What is the difference between System.String and System.StringBuilder classes?
A)System.String
is immutable.It can’t manipulate the data. System.StringBuilder can have
mutable string where a variety of operations can be performed.It can manipulate
the data.
14.
String objects are immutable?Infer the statement?
A)String
objects are immutable means, they cannot be alter they have been declared. All
of the String methods and C# operators that appear to modify a string actually
return the results in a new string object. In the following example, when the contents
of “a” and “b” are concatenated to form a single string, the two original
strings are unmodified. The += operator creates a new string that contains the
combined contents. That new object is assigned to the variable “a”, and the
original object that was assigned to “a” is released for garbage collection
because no other variable holds a reference to it.
string
a = "First String ";
string
b = "Second String";
//
Concatenate “a” and “b”. This actually creates a new
//
string object and stores it in a, releasing the
//
reference to the original object.
a
+= b;
System.Console.WriteLine(a);
//
Output: First String Second String
15.
What's the advantage of using System.Text.StringBuilder over System. String?
A)
String Builder is more efficient in the cases, where a lot of manipulation is
done to the text. Strings are immutable, so each time it's being operated on a
new instance is created.
16.Is there any difference between
string keyword and System.String class?
A)No
there is no difference between string keyword and System.String class.string
keyword is an alias for System.String class.we can use any naming convention
according to our usability levels.The String class provides many methods for
safely creating, manipulating, and comparing strings.
17.
What is a verbatim string literal and why do we use it?
A)The
"@" symbol is the verbatim string literal. Use verbatim strings for
convenience and better readability when the string text contains backslash
characters, for example in file paths. Because verbatim strings preserve new
line characters as part of the string text, they can be used to initialize
multiline strings. Use double quotation marks to embed a quotation mark inside
a verbatim string. The following example shows some common uses for verbatim
strings:
string
ImagePath = @"C:\Images\Buttons\SaveButton.jpg";
//Output:
C:\Images\Buttons\SaveButton.jpg
string
MultiLineText = @"This is multiline
Text
written to be in
three
lines.";
/*
Output:
This
is multiline
Text
written to be in
three
lines.
*/
string
DoubleQuotesString = @"My Name is "Naga Veerendra Parvataneni";
//Output:
My Name is "Naga Veerendra Parvataneni".
18.How
can we initializes a string in different forms?
A)
Form1:string stringname=””;
E.G:string a=”Welcome”;
Form2:String[] objectname=new String[]{“”,””,””};
E.G:String[] a=new String[]{”C#.Net”,”ADO.Net”,”Asp.Net”};
Form3:String objectname=new String{new[]{“”,””,””}};
E.G:String[] a=new String(new
[]{”C#.Net”,”ADO.Net”,”Asp.Net”});
It
is used for a character literals.
19.Is
String belongs to a reference type or value type?
A)String
is a reference type.It holds the address of each char in the string.
20.Is
char belongs to a reference type or value type?
A)char
belongs to a value types.It can holds a value only.
21.
What does the “@” symbol mean when it appears before the opening double quote
of a string?
A)”@”
symbol is used to instruct the compiler to ignore the actual meaning of a
symbol or a keyword.For example “\t” is a escape sequence it’s meaning is to
provide a single tab space if we use “@” preceded to “\t” escape sequence it
won’t provides a single tab space.So that means that if you want to display an
escape sequence as a text and not to work as an escape sequence, then the @
symbol can do the work for you.Generally this type of declaration is used in
Files and Streams.To display the file paths.
Example:
”C:\\Folder\\veerendra.txt”
as
String
fp=@”C:\Folder\veerendra.txt”.
22.Define
Carriage Return?
A)Carriage
Return is one of the escape sequence in C#.Net.It is often called as CR
represented with “\r” it is used to refers to a control character or mechanism
used to reset a device ‘s position to the beginning of a line of text.
23.What
is an escape sequence?Why do we use backslash characters with strings?
A)An
escape sequence has an essential mechanism to escape from the rules of a
character’s regular role and behave
differently to achieve a different purpose.It is achieved by”\”(slash)
character.Some escape sequences are listed below.
24.
What does F2 in ToString(“F2”) mean?
A)
The letter F instructs the compiler that the output number string would be
displayed up to some fixed point places after the decimal dot. The 2 after the
F signifies that the output has to be up to 2 places after the decimal dot, and
the number has to be rounded.
For
example:
double
d = 45.3920002;
string
s = d.ToString(“F2”);
The output of this would be
45.39
25.
How can you display the number 5555 of type int, as 0005555 in the output?
A)This
may be achieved by formatting the int type. The int firstly needs to be
converted to string, and then formatted for the output. See the code example
below:
Int
I = 5555;
string
s = i.ToString(“D7”);
Note
that in the value D7, D means that the output should be displayed as a decimal,
and 7 means the output should have at least 7 numerals. Now here, as the
variable ‘I’ had only 4 digits, so 3 more 0’s are padded towards the left of
the output.
26
.How can we display a decimal value as a currency string?
A)In
C#.Net many approaches are there.Here we will use “C” is used to convert any
value into currency type.Following example explores the concept:
decimal
d = 121252525.858285m;
string
ss = d.ToString("C");
Console.WriteLine(ss);
O/P:$121,252,525.86
27.How to display a number as a
percent?
A)A number with any of data
type like int or float or double or
decimal we can display % during the output.By using “P” we can display the
number successedded with % symbol.
E.G: decimal d = 12m;
string
ss = d.ToString("P");
Console.WriteLine(ss);
O/P:1,200.00%
28.How to represent a number in
Exponential format?
A)By Using “E”.
decimal d = 12m;
string
ss = d.ToString("E");
Console.WriteLine(ss);
O/P:1.200000E+001
29.How to represent a number in
hexadecimal string?
A)By Using “X”.
In hexadecimal conversion
consider only an integer types others won’t be allowed like double,decimal etc
it throws an exception invalid format.
E.G:
int
i = 123;
string
ss = i.ToString("X");
Console.WriteLine(ss);
O/P:7B
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