Strings, Bool, If..Else, Switch, Loops, Break/Continue

Question 1

A string is a sequence of characters used to represent text. It is one of the most commonly used data types for working with textual data.

What are some key characteristics of a string.

Answer 1

1. Immutable:

Strings in C# are immutable, meaning once a string is created, it cannot be changed. Any operation that modifies a string will create a new string object with the modified value, rather than altering the original string.

Example:
string str = “Hello”;
str = str + “ World”; // A new string is created; original ‘str’ is unchanged.

2. Reference Type:

Although a string represents a sequence of characters, it behaves as a reference type. This means when you assign one string to another, both variables reference the same string in memory.

Example:
string str1 = “Hello”;
string str2 = str1; // str1 and str2 now point to the same string in memory.

3. String Length:

The length of a string can be accessed using the Length property, which returns the number of characters in the string.

Example:
string str = “Hello”;
Console.WriteLine(str.Length); // Output: 5

4. String Indexing:

Strings in C# are zero-indexed, meaning the first character of the string is at index 0, the second character is at index 1, and so on.

Example:
string str = “Hello”;
char firstChar = str[0]; // ‘H’
char secondChar = str[1]; // ‘e’

5. Escape Sequences:

Strings can contain special characters using escape sequences, which are preceded by a backslash (). Common escape sequences include:
\n – Newline
\t – Tab
\ – Backslash
" – Double quote

Example:
string text = “Hello\nWorld”; // Creates a newline between “Hello” and “World”
Console.WriteLine(text);

6. String Concatenation:

You can combine strings using the + operator or string interpolation (introduced in C# 6) using $”…”.

Example:
string str1 = “Hello”;
string str2 = “World”;
string result = str1 + “ “ + str2; // Using concatenation
string interpolated = $”{str1} {str2}”; // Using string interpolation
Console.WriteLine(result); // Output: Hello World

7. String Methods: C# provides many built-in methods for working with strings. Here are some common ones:

ToUpper(): Converts all characters in a string to uppercase.

string str = “hello”;
Console.WriteLine(str.ToUpper()); // Output: HELLO

ToLower(): Converts all characters in a string to lowercase.

string str = “HELLO”;
Console.WriteLine(str.ToLower()); // Output: hello

Substring(): Extracts a substring from the string.

string str = “Hello World”;
string sub = str.Substring(0, 5); // Extracts “Hello”
Console.WriteLine(sub); // Output: Hello

Contains(): Checks if the string contains a specific substring.

string str = “Hello World”;
bool contains = str.Contains(“World”); // Returns true
Console.WriteLine(contains); // Output: True

Replace(): Replaces occurrences of a substring with a new substring.

string str = “Hello World”;
string newStr = str.Replace(“World”, “C#”);
Console.WriteLine(newStr); // Output: Hello C#

Trim(): Removes leading and trailing whitespace from the string.

string str = “ Hello World “;
string trimmed = str.Trim();
Console.WriteLine(trimmed); // Output: Hello World

8. Verbatim Strings:

In C#, you can define verbatim strings using the @ symbol. This allows the string to preserve whitespace and escape characters, making it easier to work with multi-line strings or regular expressions.

Example:
string path = @”C:\Users\JohnDoe\Documents”;
string multiline = @”This is a
multi-line
string.”;

9. Substring
   string subGreeting = greeting.Substring(0, 5);
   Console.WriteLine(subGreeting); // Output: Hello

Question 2

If statements is a conditional statement that allows you to execute a block of code only if a specified condition evaluates to true. Allowing the program to take different actions based on the outcome of a condition.

Else statements is a conditional statement that allows you to execute a block of code only if the if statement is false.

Else if statements are another form of a conditional statements that allows you to implement a new specified condition and executes the block of code if the pervious statement is false and this one is true.

Answer 2

if (condition)
{
// Execute if true
}
else if (condition)
{
// Execute if true
}
else
{
// Execute if false
}

Question 3

A bool (short for Boolean) is a fundamental data type used to represent true/false values. It is one of the most commonly used data types for making logical decisions and controlling the flow of a program through conditional expressions and loops.

Answer 3

bool is_true = True;
bool is_false = False;

Question 4

A nested if statement is a if statements inside of a if statement

Answer 4

if (condition)
{
if (condition)
{
// Do
}
else
{
// Do
}
}

Question 5

The switch statement is a control structure used to execute one out of many possible blocks of code, depending on the value of an expression. It’s typically used as a more readable alternative to multiple if-else if chains when you need to check the value of a variable against many different possibilities.

Answer 5

switch (expression)
{
case value1:
// Code to execute if expression == value1
break;

case value2:
    // Code to execute if expression == value2
    break;

default:
    // Code to execute if no case matches the expression
    break; } expression: The value that is being tested.

case: Each case checks if the value of the expression matches the specified value. If a match is found, the associated block of code is executed.

break: The break statement is used to exit the switch block after executing a case. If you omit break, the code will “fall through” and continue to execute subsequent case blocks.

default: This is an optional block that is executed if no case matches the expression.

Question 6

When should you use if statements over switch cases and switch cases over if statements?

Answer 6

// Switch over if statements
// - Multiple Distinct Options
// - Improves Readability, easier code to read
// - Enum Types, allows to evaluate each enumeration value explicitly

// If statements over switch cases
// - Complex Conditions, handles complex logical conditions that involve multiple comparisons or boolean expressions
// - Ranged Values, checking if a value falls in a certain range
// - Dynamic Conditions, can handle conditions that may change on runtime whereas switch statements work better with static, predefined options.

Question 7

Loops are control structures that allow you to execute a block of code repeatedly as long as a certain condition is met.

for loop is typically used when you know in advance how many times you need to execute a block of code.

for (int i = 0; i < 5; i++)
{
Console.WriteLine(i);
}

while loop is used when you want to continue executing a block of code as long as a specific condition remains true.

while (condition)
{
// Do
}

do-while loop is similar to the while loop but guarantees that the code inside the loop will be executed at least once before checking the condition.

do
{
// Do
}
while (condition)

foreach loop is used to iterate over a collection (such as an array, list, or other enumerable types) without having to manually manage the loop index. It’s ideal when you want to access each item in a collection one by one.

foreach (type item in collection)
{
// code to execute with each item
}

Answer 7

….

Question 8

break and continue are used in loops but what for?

Answer 8

break: Immediately exits the loop, regardless of the condition.

continue: Skips the current iteration and moves to the next iteration of the loop.