102 lines
2.5 KiB
Markdown
102 lines
2.5 KiB
Markdown
---
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title: If
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---
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# If
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The if statement executes different blocks of code based on conditions.
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```
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if (condition)
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{
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// Do something when `condition` is true
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}
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else
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{
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// Do something when `condition` is false
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}
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```
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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.
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instead of writing:
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```
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if (condition)
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{
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// Do something if `condition` is true
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}
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else
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{
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if (anotherCondition)
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{
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// Do something if `anotherCondition` is true
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}
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else
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{
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// Do something if `condition` AND `anotherCondition` is false
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}
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}
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```
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You could use the much more concise writing:
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```
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if (condition)
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{
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// Do something if `condition` is true
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}
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else if (anotherCondition)
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{
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// Do something if `anotherCondition` is ture
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}
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else
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{
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// Do something if `condition` AND `anotherCondition` is false
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}
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```
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It is also possible to check if the condition is false and act on it without it having to have an else statement.
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```
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if(!condition)
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{
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//do something if the condition is false
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}
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```
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```
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int number = 3;
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//!= implies that you wish to check if the object's value is not equal to the value next to it
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if(number !=2)
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{
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Console.WriteLine("Number is not 2");
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}
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```
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Note that the `else` and `else if` sections are not required, while `if` is mandatory.
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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.
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## Example
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```
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Console.WriteLine("Who are you? ");
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string name = Console.ReadLine();
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if (name == "John")
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{
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Console.WriteLine("Hi John!");
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}
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else if (name == "Fabio")
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{
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Console.WriteLine("Oh, it's you Fabio :)");
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}
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else
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{
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Console.WriteLine("Oh! I thought you were John or Fabio. Anyway, nice to meet you {0}!", name);
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}
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/* Run and type some names:
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-> If name is "John", then output is "Hi John!"
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-> If name is "Fabio", then output is "Oh, it's you Fabio :)"
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-> 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.
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*/
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```
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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.
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