Integer types and their ranges in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of integer overflow in C#

What is the output of the following C# code snippet?

C Sharp (C#)

checked
{
    byte b = 255;
    b = (byte)(b + 1);
    Console.WriteLine(b);
}

A OverflowException

B 255

C 0

D 256

💡 Hint

The checked block throws an exception on overflow.

The byte type can hold values from 0 to 255. Adding 1 causes an overflow. The checked block causes an OverflowException to be thrown.

❓ Predict Output

intermediate

Range of Int16 type

What is the output of this C# code?

C Sharp (C#)

short min = short.MinValue;
short max = short.MaxValue;
Console.WriteLine($"{min} {max}");

A -65536 65535

B -32767 32768

C -32768 32767

D -128 127

💡 Hint

Short is a 16-bit signed integer.

The Int16 (short) type ranges from -32768 to 32767.

❓ Predict Output

advanced

Unsigned integer max value output

What does this C# code print?

C Sharp (C#)

uint max = uint.MaxValue;
Console.WriteLine(max);

A 4294967295

B -1

C 2147483647

D 0

💡 Hint

uint is a 32-bit unsigned integer.

The uint type ranges from 0 to 4294967295. MaxValue is 4294967295.

❓ Predict Output

advanced

Behavior of integer underflow in unchecked context

What is the output of this C# code?

C Sharp (C#)

unchecked
{
    int min = int.MinValue;
    int result = min - 1;
    Console.WriteLine(result);
}

A OverflowException

B -2147483649

C -2147483648

D 2147483647

💡 Hint

Unchecked context allows silent overflow/underflow.

int.MinValue is -2147483648. Subtracting 1 causes underflow and wraps around to 2147483647 in unchecked context.

🧠 Conceptual

expert

Size and range of long type in C#

Which of the following correctly describes the size and range of the C# long type?

A 32-bit signed integer ranging from -2,147,483,648 to 2,147,483,647

B 64-bit signed integer ranging from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

C 64-bit unsigned integer ranging from 0 to 18,446,744,073,709,551,615

D 16-bit signed integer ranging from -32,768 to 32,767

💡 Hint

long is a 64-bit signed integer in C#.

The long type in C# is a 64-bit signed integer with the specified range.

Practice

1. Which C# integer type can store values from -128 to 127?

easy

A. int

B. byte

C. short

D. sbyte

Solution

1. Step 1: Recall the range of sbyte

   The sbyte type stores signed 8-bit integers from -128 to 127.

2. Step 2: Compare with other types

   byte stores 0 to 255 (unsigned), short stores -32,768 to 32,767, and int stores much larger values.

3. Final Answer:

   sbyte -> Option D

4. Quick Check:

   Range -128 to 127 = sbyte [OK]

Hint: Remember sbyte is signed 8-bit: -128 to 127 [OK]

Common Mistakes:

• Confusing byte (unsigned) with sbyte
• Choosing short which has a larger range
• Assuming int is smallest

2. Which of the following is the correct way to declare a variable of type uint in C#?

easy

A. uint number = -1;

B. uint number = 4294967295;

C. uint number = 4294967296;

D. uint number = 3.14;

Solution

1. Step 1: Understand uint range

   uint is unsigned 32-bit integer with range 0 to 4,294,967,295.

2. Step 2: Check each assignment

   uint number = -1; assigns -1 (negative) which is invalid. uint number = 4294967295; assigns max valid value 4,294,967,295. uint number = 4294967296; assigns 4,294,967,296 which is too large. uint number = 3.14; assigns a decimal which is invalid for integer type.

3. Final Answer:

   uint number = 4294967295; -> Option B

4. Quick Check:

   uint max = 4294967295 [OK]

Hint: uint stores 0 to 4,294,967,295 only [OK]

Common Mistakes:

• Assigning negative values to unsigned types
• Using values larger than max range
• Assigning decimal numbers to integer types

3. What will be the output of this C# code?

short a = 30000;
short b = 10000;
int c = a + b;
Console.WriteLine(c);

medium

A. 40000

B. -25536

C. OverflowException

D. Compile-time error

Solution

1. Step 1: Understand variable types and addition

   Variables a and b are short (16-bit signed), but addition promotes them to int automatically.

2. Step 2: Calculate the sum and output

   30000 + 10000 = 40000 fits in int range, so c stores 40000 and prints it.

3. Final Answer:

   40000 -> Option A

4. Quick Check:

   30000 + 10000 = 40000 [OK]

Hint: short addition promotes to int, no overflow here [OK]

Common Mistakes:

• Expecting overflow because sum exceeds short max
• Thinking addition stays in short type
• Confusing runtime overflow with compile error

4. Identify the error in this C# code snippet:

byte x = 255;
byte y = 1;
byte z = (byte)(x + y);
Console.WriteLine(z);

medium

A. Output is 0 due to overflow wrap-around

B. Compile-time error due to overflow

C. No error, output is 256

D. Runtime exception thrown

Solution

1. Step 1: Analyze addition and casting

   Addition of x + y is done as int (255 + 1 = 256). Casting to byte truncates to 8 bits.

2. Step 2: Understand overflow wrap-around

   Since byte max is 255, 256 wraps around to 0 due to overflow without exception.

3. Final Answer:

   Output is 0 due to overflow wrap-around -> Option A

4. Quick Check:

   256 mod 256 = 0 [OK]

Hint: Casting int > 255 to byte wraps around [OK]

Common Mistakes:

• Expecting output 256 which is invalid for byte
• Thinking compile or runtime error occurs
• Ignoring overflow wrap-around behavior

5. You need to store the population of a city which can be up to 5 billion. Which C# integer type should you use to avoid overflow?

hard

A. int

B. uint

C. long

D. short

Solution

1. Step 1: Check the required range

   5 billion is 5,000,000,000 which exceeds int max (2,147,483,647) and uint max (4,294,967,295).

2. Step 2: Choose type with sufficient range

   long is a signed 64-bit integer with range ±9 quintillion, enough to store 5 billion safely.

3. Final Answer:

   long -> Option C

4. Quick Check:

   5 billion < long max [OK]

Hint: Use long for numbers bigger than int or uint max [OK]

Common Mistakes:

• Choosing int or uint which are too small
• Using short which is very small
• Not considering signed vs unsigned range