add: strings and projects

20-project-spam-masker/README.md

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+# Spam Masker Challenge Tips
+
+## Rules:
+
+* You shouldn't use a standard library function.
+
+* You should only solve the challenge by manipulating the bytes directly.
+
+* Manipulate the bytes of a string using indexing, slicing, appending etc.
+
+* Be efficient: Do not use string concat (+ operator).
+	* Instead, create a new byte slice as a buffer from the given string argument.
+	* Then, manipulate it during your program.
+	* And, for once, print that buffer.
+
+* Mask only links starting with `http://`
+
+* Don't check for uppercase/lowercase letters
+
+	* The goal is learning how to manipulate bytes in strings, it's not about creating the perfect masker.
+
+	* For example: A spammer can prevent the masker like this (for now this is OK):
+
+	  ```
+      "Here's my spammy page: hTTp://youth-elixir.com"
+                               ^^
+      ```
+
+* But, you should catch this:
+
+  ```
+  INPUT:
+  Here's my spammy page: http://hehefouls.netHAHAHA see you.
+
+  OUTPUT:
+  Here's my spammy page: http://******************* see you.
+  ```
+
+## Steps:
+
+1. Check whether there's a command line argument or not. If not, quit from the program with a message.
+
+2. Create a byte buffer as big as the argument.
+
+3. Loop and detect the `http://` patterns
+
+4. Copy the input character by character to the buffer
+
+5. If you detect `http://` pattern, copy the `http://` first, then copy the `*`s instead of the original link until you see whitespace character.
+
+    For example: 
+    ```
+	INPUT:
+    Here: http://www.mylink.com Click!
+
+    OUTPUT:
+	Here: http://************** Click!
+    ```
+
+6. Print the buffer as a string