2.5 KiB
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If |
If
The if statement executes different blocks of code based on conditions.
if (condition)
{
// Do something when `condition` is true
}
else
{
// Do something when `condition` is false
}
When condition
is true, code inside the if
section executes, otherwise else
executes. Sometimes you would need to add a second condition. For readability, you should use else if
rather than nesting if
statements.
instead of writing:
if (condition)
{
// Do something if `condition` is true
}
else
{
if (anotherCondition)
{
// Do something if `anotherCondition` is true
}
else
{
// Do something if `condition` AND `anotherCondition` is false
}
}
You could use the much more concise writing:
if (condition)
{
// Do something if `condition` is true
}
else if (anotherCondition)
{
// Do something if `anotherCondition` is ture
}
else
{
// Do something if `condition` AND `anotherCondition` is false
}
It is also possible to check if the condition is false and act on it without it having to have an else statement.
if(!condition)
{
//do something if the condition is false
}
int number = 3;
//!= implies that you wish to check if the object's value is not equal to the value next to it
if(number !=2)
{
Console.WriteLine("Number is not 2");
}
Note that the else
and else if
sections are not required, while if
is mandatory.
Also note that if the code following your conditional statement is a single line; you do not have to put the brackets around that code - but the brackets help for readability.
Example
Console.WriteLine("Who are you? ");
string name = Console.ReadLine();
if (name == "John")
{
Console.WriteLine("Hi John!");
}
else if (name == "Fabio")
{
Console.WriteLine("Oh, it's you Fabio :)");
}
else
{
Console.WriteLine("Oh! I thought you were John or Fabio. Anyway, nice to meet you {0}!", name);
}
/* Run and type some names:
-> If name is "John", then output is "Hi John!"
-> If name is "Fabio", then output is "Oh, it's you Fabio :)"
-> If name is neither "John" nor "Fabio", output is "Oh! I thought you were John or Fabio. Anyway, nice to meet you {0}!" where {0} contains the name.
*/
The if statement needs a boolean result, that is, true or false. In some programming languages, several datatypes can be automatically converted into booleans, but in C#, you have to specifically make the result boolean. For instance, you can't use if(number), but you can compare number to something, to generate a true or false.