DAY 5

Functions

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Functions let us wrap up pieces of code so they can be used in lots of places. We can send data into functions to customize how they work, and get back data that tells us the result that was calculated.

Believe it or not, function calls used to be really slow. Steve Johnson, the author of many early coding tools for the Unix operating system, said this:

“Dennis Ritchie (the creator of the C programming language) encouraged modularity by telling all and sundry that function calls were really, really cheap in C. Everybody started writing small functions and modularizing. Years later we found out that function calls were still expensive, and our code was often spending 50% of its time just calling them. Dennis had lied to us! But it was too late; we were all hooked...”

Today you have 11 one-minute videos to watch, and you’ll meet things like variadic functions, throwing errors, and more. Once you’ve watched each video and optionally gone through the extra reading, there’s a short test to help make sure you’ve understood what was taught.

1. Writing functions
   • Optional: What code should be put in a function?
   • Test: Writing functions
2. Accepting parameters
   • Optional: How many parameters should a function accept?
   • Test: Accepting parameters
3. Returning values
   • Optional: When is the return keyword not needed in a Swift function?
   • Optional: How can you return two or more values from a function?
   • Test: Returning values
4. Parameter labels
   • Optional: Why does Swift use parameter labels?
   • Test: Parameter labels
5. Omitting parameter labels
   • Optional: When should you omit a parameter label?
   • Test: Omitting parameter labels
6. Default parameters
   • Optional: When to use default parameters for functions
   • Test: Default parameters
7. Variadic functions
   • Optional: When to use variadic functions
   • Test: Variadic functions
8. Writing throwing functions
   • Optional: When should you write throwing functions?
   • Test: Writing throwing functions
9. Running throwing functions
   • Optional: Why does Swift make us use try before every throwing function?
   • Test: Running throwing functions
10. inout parameters
    • Optional: When should you use inout parameters?
    • Test: inout parameters
11. Functions summary
    • Test: Test

Do you remember the two rules of this series? You’re already being awesome at the first one because you keep coming back for more (you rock!), but don’t forget the second: post your progress online, so you can benefit from all the encouragement.

Need help? Tweet me @twostraws!

 

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