C# Questions & Answers onType Conversion in Expressions for Freshers

1. What is the need for ‘Conversion of data type’ in C#?

a) To store a value of one data type into a variable of another data type
b) To get desired data
c) To prevent situations of run time error during change or conversion of data type
d) None of the mentioned

Answer: c

Explanation: By Definition.

2. Types of ‘Data Conversion’ in C#?

a) Implicit Conversion
b) Explicit Conversion
c) Implicit Conversion and Explicit Conversion
d) None of the mentioned

Answer: b

Explanation: By Definition.

3.’Implicit Conversion’ follows the order of conversion as per compatibility of datatype as :

a) float < char < int
b) char < int < float
c) int < char < float
d) float < int < char

Answer: b

4. For the given set of code select the relevant solution for conversion of data type.

1.  static void Main(string[] args)

2.  {

3.      int num1 = 20000;

4.      int num2 = 50000;

5.      long total;

6.      total = num1 + num2;

7.      Console.WriteLine("Total is : " +total);

8.      Console.ReadLine();

9.  }

a) Compiler will generate runtime error
b) Conversion is implicit type, no error generation
c) Specifying datatype for conversion externally will solve the problem
d) None of the mentioned

Answer: b

Explanation: Since,conversion of datatype is implicit type as ‘int’ is a subset of ‘longtype’ hence no need to explicitly convert data from one type to another.Compiler will automatically do conversion.
Output : Total is : 70000.

5. Subset of ‘int’ datatype is :
a) long ,ulong, ushort
b) long, ulong, uint
c) long, float, double
d) long, float, ushort

Answer: c

Explanation: By definition.

6. Type of Conversion in which compiler is unable to convert the datatype implicitly is ?
a) ushort to long
b) int to uint
c) ushort to long
d) byte to decimal

Answer:b

Explanation: ‘int’ is 32 bit signed integer whereas ‘uint’ is 32 bit unsigned integer .Range of int is larger than uint.So,compiler cannot implicitly convert from larger datatype to smaller datatype.

7. Disadvantages of Explicit Conversion are ?
a) Makes program memory heavier
b) Results in loss of data
c) Potentially Unsafe
d) None of the mentioned

Answer: b

Explanation: By definition.

8. For the given set of code, is conversion possible?

1.  static void Main(string[] args)

2.  {

3.      int a = 76;

4.      char b;

5.      b = (char)a;

6.      Console.WriteLine(b);

7.      Console.ReadLine();

8.  }

a) Compiler will generate runtime error
b) Conversion is explicit type
c) Compiler will urge for conversion from ‘integer’ to ‘character’ datatype
d) None of the mentioned

Answer: b

Explanation: Since, given conversion is of explicit type as one datatype is in integer and other is in ‘char’.Compiler is needed to make a clear distinction between both type of datatypes and hence,explicitly one need to specify datatype as compiler is unable to make automatic conversion.
Output : L.

9. Predict the relevant output for the given set of code.

1. static void Main(string[] args)

2. {

3.     float sum;

4.     int i;

5.     sum = 0.0F;

6.     for (i = 1; i <= 10; i++)

7.     {

8.         sum = sum + 1 /(float)i;

9.     }

10.     Console.WriteLine("sum =" +sum);

11.     Console.ReadLine();

12. }

a) 2.000
b) 2.910
c) 2.928
d) 3.000

Answer: c

Output : sum = 2.928698.

10) Which of the conversions are valid for the given set of code?

1.  static void Main(string[] args)

2.  {

3.      int a = 22;

4.      long b = 44;

5.      double c = 1.406;

6.      b = a;

7.      c = a;

8.      a = b;

9.      b = c;

10.  }

a) c = a, b = c
b) a = c, b = a
c) b = a, c = a
d) All of the mentioned

Answer: a

Explanation: Conversion of data type from ‘int’ to ‘double’ is implicit in nature for ‘c = a’ as int is subset of double but same is not applicable for ‘b = c’ as ‘c’ had wider scope of data range then ‘b’ so explicit conversion is needed.
Output :
Error 1 :Cannot implicitly convert type ‘long’ to ‘int’. An explicit conversion exists (are you missing a cast?).
Error 2 :Cannot implicitly convert type ‘double’ to ‘long’. An explicit conversion exists (are you missing a cast?).

Correct solution :

 static void Main(string[] args)
 {
     int a = 22;
     long b = 44;
     double c = 1.406;
     b = a;
     c = a;
     a = (int)b;
     b = (long)c;
 }