## C# `if` and `else` Conditional Statements
### Explanation
Conditional statements in C# allow you to execute certain blocks of code based on whether a condition is true or false. The most common conditional statements are `if` and `else`.
### Theory
#### `if` Statement
An `if` statement evaluates a boolean expression and executes a block of code if the expression is true. The syntax is:
```csharp
if (condition)
{
// Code to be executed if condition is true
}
```
#### `else` Statement
An `else` statement follows an `if` statement and executes a block of code if the `if` condition is false. The syntax is:
```csharp
if (condition)
{
// Code to be executed if condition is true
}
else
{
// Code to be executed if condition is false
}
```
#### `else if` Statement
An `else if` statement allows you to check multiple conditions. If the initial `if` condition is false, the `else if` condition is evaluated. The syntax is:
```csharp
if (condition1)
{
// Code to be executed if condition1 is true
}
else if (condition2)
{
// Code to be executed if condition2 is true
}
else
{
// Code to be executed if both condition1 and condition2 are false
}
```
### Diagram
Here is a flowchart representing the `if-else` structure:
```
+------------------+
| Condition 1 |
+------------------+
|
+----------+----------+
| true | false
v v
+---------------+ +------------------+
| Execute Code | | Condition 2 |
+---------------+ +------------------+
|
+----------+----------+
| true | false
v v
+---------------+ +----------------+
| Execute Code | | Execute Code |
+---------------+ +----------------+
```
### Examples
#### Example 1: Checking a Number
Here is an example of an `if-else` statement in C# that checks if a number is positive, negative, or zero:
```csharp
using System;
class Program
{
static void Main()
{
int number = 10;
if (number > 0)
{
Console.WriteLine("The number is positive.");
}
else if (number < 0)
{
Console.WriteLine("The number is negative.");
}
else
{
Console.WriteLine("The number is zero.");
}
}
}
```
**Output**:
```
The number is positive.
```
#### Example 2: Checking User Input
Here is an example of using `if-else` statements to validate user input:
```csharp
using System;
class Program
{
static void Main()
{
Console.Write("Enter a number: ");
string input = Console.ReadLine();
int number;
if (int.TryParse(input, out number))
{
if (number % 2 == 0)
{
Console.WriteLine("The number is even.");
}
else
{
Console.WriteLine("The number is odd.");
}
}
else
{
Console.WriteLine("Invalid input.");
}
}
}
```
**Output** (Example 1):
```
Enter a number: 4
The number is even.
```
**Output** (Example 2):
```
Enter a number: hello
Invalid input.
```
#### Example 3: Grading System
Here is an example of using `if-else` statements to determine the grade based on a score:
```csharp
using System;
class Program
{
static void Main()
{
int score = 85;
if (score >= 90)
{
Console.WriteLine("Grade: A");
}
else if (score >= 80)
{
Console.WriteLine("Grade: B");
}
else if (score >= 70)
{
Console.WriteLine("Grade: C");
}
else if (score >= 60)
{
Console.WriteLine("Grade: D");
}
else
{
Console.WriteLine("Grade: F");
}
}
}
```
**Output**:
```
Grade: B
```
### Summary
Conditional statements using `if` and `else` in C# are essential for controlling the flow of a program based on specific conditions. They allow for decision-making processes within your code, enabling different outcomes based on varying conditions. This is fundamental for creating dynamic and responsive applications.
No comments:
Post a Comment
Thanks for the contribution, our team will check and reply back if response required.