Integer types and their ranges in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the range of the int type in C#?

The int type in C# is a 32-bit signed integer. It ranges from -2,147,483,648 to 2,147,483,647.

beginner

What is the difference between int and uint in C#?

int is a signed 32-bit integer (can hold negative and positive numbers). uint is an unsigned 32-bit integer (only positive numbers and zero). uint ranges from 0 to 4,294,967,295.

intermediate

What is the size and range of the long type in C#?

long is a 64-bit signed integer. It ranges from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.

beginner

Which integer type would you use to store only positive numbers up to about 65,000?

You would use ushort, which is an unsigned 16-bit integer ranging from 0 to 65,535.

intermediate

What happens if you try to store a number outside the range of an integer type in C#?

If you store a number outside the range, it causes an overflow. By default, this can wrap around silently or throw an exception if checked context is used.

What is the range of the byte type in C#?

A 0 to 65,535

B -128 to 127

C -32,768 to 32,767

D 0 to 255

byte is an unsigned 8-bit integer ranging from 0 to 255.

Which type is a 16-bit signed integer in C#?

A short

B ushort

C int

D long

short is a 16-bit signed integer ranging from -32,768 to 32,767.

What is the size of the uint type in C#?

A 8 bits

B 16 bits

C 32 bits

D 64 bits

uint is a 32-bit unsigned integer.

Which integer type can store the largest positive number?

A long

B int

C ushort

D byte

long is a 64-bit signed integer and can store the largest positive number among these.

What keyword can you use to detect overflow errors in C#?

A overflow

B checked

C unchecked

D safe

The checked keyword enables overflow checking and throws exceptions on overflow.

Explain the difference between signed and unsigned integer types in C# and give examples.

Think about whether the number can be negative or not.

List the common integer types in C# and their size in bits.

Remember the smallest to largest sizes.

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