49 lines
883 B
Markdown
49 lines
883 B
Markdown
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---
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tags:
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- C
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---
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In order to create a file that you can import into other C files you need to
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create a header file.
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> Remember that this isn't really a module since `.h` files and `#includes` are
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> just text substition
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In fact you create a `.h` header file which links to a `.c` file which actually
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contains the code you want to import.
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Let's say we want to create a "module" that handles connecting to WiFi:
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```c
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// wifi.h
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#ifndef WIFI_H
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#define WIFI_H
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void wifi_connect(void);
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#endif
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```
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In the `.h` file we just define the function signature and put checks (so it
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doesn't get redefined).
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Then the implementation file:
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```c
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// main/wifi.c
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// Add any header files or auxiliary functions that the main (wifi_connect)
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// function will require here
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void wifi_connect(void) {}
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```
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Then in your main entrypoint:
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```c
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// main/main.c
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#include "wifi.h"
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wifi_connect()
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```
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