Type conversion and casting in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Type conversion and casting

Start with variable

↓

Check if implicit conversion possible?

No→Explicit cast needed

↓

Apply explicit cast

↓

Convert value

↓

Check cast success

↓

Use converted value

↓

End

Start with a variable, check if automatic conversion works; if not, use explicit cast, then use the converted value.

Execution Sample

C Sharp (C#)

int i = 100;
long l = i; // implicit conversion
int j = (int)l; // explicit cast
Console.WriteLine(j);

Converts int to long implicitly, then casts long to int explicitly, and prints the int value.

Execution Table

Step	Action	Variable	Value Before	Value After	Notes
1	Declare int i	i	undefined	100	Initialize i with 100
2	Implicit conversion int to long	l	undefined	100	No cast needed, long can hold int
3	Explicit cast long to int	j	undefined	100	Cast long to int explicitly
4	Print j	j	100	100	Output is 100
5	End	-	-	-	Program ends

💡 All conversions done, program ends after printing int value.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
i	undefined	100	100	100	100
l	undefined	undefined	100	100	100
j	undefined	undefined	undefined	100	100

Key Moments - 2 Insights

Why can int convert to long without a cast but long to int needs a cast?

Because long can hold all int values safely (implicit conversion), but converting long to int might overflow or lose data (narrowing), so C# requires an explicit cast (see steps 2 and 3 in execution_table).

What happens if you try to assign a long to an int without casting?

It causes a compile-time error because int might not hold the larger long value safely, so explicit cast is required to tell the compiler you accept possible data loss.

Visual Quiz - 3 Questions

Look at the execution_table at step 2, what is the value of variable 'l' after implicit conversion?

A undefined

B 0

C 100

D 100.0

💡 Hint

Check the 'Value After' column for variable 'l' at step 2 in execution_table.

At which step does the explicit cast happen?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look for the action mentioning 'Explicit cast' in execution_table.

If we remove the explicit cast from long to int, what will happen?

A Compile-time error due to missing cast

B Code compiles and runs fine

C Runtime error occurs

D Value of j becomes zero

💡 Hint

Recall C# rules for implicit vs explicit conversion shown in concept_flow and key_moments.

Concept Snapshot

Type conversion in C# can be implicit or explicit.
Implicit conversion happens when no data loss is possible.
Explicit casting is needed when data loss or narrowing may occur.
Syntax for explicit cast: (TargetType)variable.
Always ensure safe conversions to avoid errors.

Full Transcript

This lesson shows how C# converts types. First, an int variable 'i' is set to 100. Then it converts implicitly to a long variable 'l' because long can hold all int values safely. Next, 'l' is explicitly cast to an int 'j' because converting from long to int is narrowing and might cause overflow or data loss, so C# requires a cast. Finally, the int value is printed. The execution table tracks each step and variable value. Key points include when implicit conversion is allowed and when explicit casting is needed to avoid errors. The quiz tests understanding of these steps and rules.