21 lines
1.1 KiB
HTML
21 lines
1.1 KiB
HTML
<p>
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Remember the line from the hello world program <b>#include <stdio.h></b>?
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This is a instruction for the preprocessor to include a library to your code.
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More specifically the standard library stdio.h. Libraries are a <b>set of functions
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and data structure</b> you can use to make your live easier.
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They are tested and optimized but more importantly; You don't have to write
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everything by hand.
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</p>
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<p>
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We talk about functions and data structures later. All you need to know is,
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that they are like complex instruction you can call. Like the printf function we were using
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in the beginning. Printf is a function that takes a string with placeholders, which specify the format
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(hence the name printf print formated), and the inputs for the placeholders. With that it builds the final string
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and prints it out to the standard output.
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</p>
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<p>
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There are many useful libraries you can use. The standard libraries every compiler has to provide, 3rd party libraries you
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can download or libraries you can write your self to reuse them later.
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We will use the math.h library in this example.
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</p>
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