Selections
Selection statements are used to control the flow of a program based on conditions. The two primary selection statements in C# are if
and switch
. These statements allow you to execute different blocks of code depending on whether a certain condition is true or false.
If Statements
The if statement is used to execute a block of code if a specified condition is true
. It can also be followed by an optional else statement to execute a different block of code if the condition is false
.
double grade = 77.4;
char letterGrade = 'F';
if (grade > 90)
{
letterGrade = 'A';
}
else if (grade > 80)
{
letterGrade = 'B';
}
else if (grade > 70)
{
letterGrade = 'C';
}
else if (grade > 60)
{
letterGrade = 'D';
}
Console.WriteLine("Final grade: {0}", letterGrade);
Output:
Switch Statements
The switch statement is used to select one of many code blocks to be executed. It is often used when you have multiple possible values to compare.
DateTime date = DateTime.Now;
string message = "";
switch (date.DayOfWeek)
{
case DayOfWeek.Sunday:
case DayOfWeek.Saturday:
message = "It's the weekend!";
break;
case DayOfWeek.Monday:
case DayOfWeek.Tuesday:
message = "Is it the weekend yet?";
break;
case DayOfWeek.Wednesday:
message = "It's midweek.";
break;
case DayOfWeek.Thursday:
case DayOfWeek.Friday:
message = "Almost the weekend. :)";
break;
}
Console.WriteLine("{0}: {1}", date.DayOfWeek, message);
Output:
Conditional Operator
The conditional (ternary) operator (? :) provides a concise way to express simple if-else statements needed to decide between one of two values.
double grade = 96.2;
Console.WriteLine("You scored {0}. You {1}.", grade, grade > 50 ? "passed" : "failed");
Output: