Merge 'master' of github.com:adambard/learnxinyminutes-docs

bash.html.markdown

@@ -90,17 +90,26 @@ else
     echo "Your name is your username"
 fi
 
+# NOTE: if $Name is empty, bash sees the above condition as:
+if [ -ne $USER ]
+# which is invalid syntax
+# so the "safe" way to use potentially empty variables in bash is:
+if [ "$Name" -ne $USER ] ...
+# which, when $Name is empty, is seen by bash as:
+if [ "" -ne $USER ] ...
+# which works as expected
+
 # There is also conditional execution
 echo "Always executed" || echo "Only executed if first command fails"
 echo "Always executed" && echo "Only executed if first command does NOT fail"
 
 # To use && and || with if statements, you need multiple pairs of square brackets:
-if [ $Name == "Steve" ] && [ $Age -eq 15 ]
+if [ "$Name" == "Steve" ] && [ "$Age" -eq 15 ]
 then
     echo "This will run if $Name is Steve AND $Age is 15."
 fi
 
-if [ $Name == "Daniya" ] || [ $Name == "Zach" ]
+if [ "$Name" == "Daniya" ] || [ "$Name" == "Zach" ]
 then
     echo "This will run if $Name is Daniya OR Zach."
 fi

c.html.markdown

@@ -6,8 +6,8 @@ contributors:
     - ["Árpád Goretity", "http://twitter.com/H2CO3_iOS"]
     - ["Jakub Trzebiatowski", "http://cbs.stgn.pl"]
     - ["Marco Scannadinari", "https://marcoms.github.io"]
+    - ["Zachary Ferguson", "https://github.io/zfergus2"]
     - ["himanshu", "https://github.com/himanshu81494"]
-
 ---
 
 Ah, C. Still **the** language of modern high-performance computing.
@@ -54,6 +54,8 @@ int function_2(void);
 // Must declare a 'function prototype' before main() when functions occur after
 // your main() function.
 int add_two_ints(int x1, int x2); // function prototype
+// although `int add_two_ints(int, int);` is also valid (no need to name the args),
+// it is recommended to name arguments in the prototype as well for easier inspection
 
 // Your program's entry point is a function called
 // main with an integer return type.
@@ -74,6 +76,9 @@ int main (int argc, char** argv)
   ///////////////////////////////////////
   // Types
   ///////////////////////////////////////
+
+  // All variables MUST be declared at the top of the current block scope
+  // we declare them dynamically along the code for the sake of the tutorial
 
   // ints are usually 4 bytes
   int x_int = 0;
@@ -232,7 +237,7 @@ int main (int argc, char** argv)
   0 || 1; // => 1 (Logical or)
   0 || 0; // => 0
 
-  // Conditional expression ( ? : )
+  // Conditional ternary expression ( ? : )
   int e = 5;
   int f = 10;
   int z;
@@ -302,6 +307,8 @@ int main (int argc, char** argv)
   for (i = 0; i <= 5; i++) {
     ; // use semicolon to act as the body (null statement)
   }
+  // Or
+  for (i = 0; i <= 5; i++);
 
   // branching with multiple choices: switch()
   switch (a) {
@@ -678,8 +685,56 @@ typedef void (*my_fnp_type)(char *);
 // ,                                 | left to right //
 //---------------------------------------------------//
 
-```
+/******************************* Header Files **********************************
+
+Header files are an important part of c as they allow for the connection of c 
+source files and can simplify code and definitions by seperating them into 
+seperate files.
+
+Header files are syntaxtically similar to c source files but reside in ".h" 
+files. They can be included in your c source file by using the precompiler 
+command #include "example.h", given that example.h exists in the same directory 
+as the c file.
+*/
+
+/* A safe guard to prevent the header from being defined too many times. This */
+/* happens in the case of circle dependency, the contents of the header is    */
+/* already defined.                                                           */
+#ifndef EXAMPLE_H /* if EXAMPLE_H is not yet defined. */
+#define EXAMPLE_H /* Define the macro EXAMPLE_H. */
+
+/* Other headers can be included in headers and therefore transitively */
+/* included into files that include this header.                       */
+#include <string.h>
 
+/* Like c source files macros can be defined in headers and used in files */
+/* that include this header file.                                         */
+#define EXAMPLE_NAME "Dennis Ritchie"
+/* Function macros can also be defined. */
+#define ADD(a, b) (a + b)
+
+/* Structs and typedefs can be used for consistency between files. */
+typedef struct node
+{
+    int val;
+    struct node *next;
+} Node;
+
+/* So can enumerations. */
+enum traffic_light_state {GREEN, YELLOW, RED};
+
+/* Function prototypes can also be defined here for use in multiple files,  */
+/* but it is bad practice to define the function in the header. Definitions */
+/* should instead be put in a c file.                                       */
+Node createLinkedList(int *vals, int len);
+
+/* Beyond the above elements, other definitions should be left to a c source */
+/* file. Excessive includeds or definitions should, also not be contained in */
+/* a header file but instead put into separate headers or a c file.          */
+
+#endif /* End of the if precompiler directive. */
+
+```
 ## Further Reading
 
 Best to find yourself a copy of [K&R, aka "The C Programming Language"](https://en.wikipedia.org/wiki/The_C_Programming_Language)

cs-cz/python3.html.markdown

@@ -48,7 +48,7 @@ Poznámka: Tento článek je zaměřen na Python 3. Zde se můžete [naučit sta
 -5 // 3      # => -2
 -5.0 // 3.0  # => -2.0
 
-# Pokud použiteje desetinné číslo, výsledek je jím také
+# Pokud použijete desetinné číslo, výsledek je jím také
 3 * 2.0  # => 6.0
 
 # Modulo
@@ -420,7 +420,7 @@ next(iterator)  # Vyhodí StopIteration
 ## 4. Funkce
 ####################################################
 
-# Pro vytvoření nové funkce použijte def
+# Pro vytvoření nové funkce použijte klíčové slovo def
 def secist(x, y):
     print("x je {} a y je {}".format(x, y))
     return x + y  # Hodnoty se vrací pomocí return
@@ -520,7 +520,7 @@ class Clovek(object):
     # podtržítka na začátku a na konci značí, že se jedná o atribut nebo
     # objekt využívaný Pythonem ke speciálním účelům, ale můžete sami
     # definovat jeho chování. Metody jako __init__, __str__, __repr__
-    # a další se nazývají "magické metody". Nikdy nepoužívejte toto
+    # a další se nazývají "magické metody". Nikdy nepoužívejte toto
     # speciální pojmenování pro běžné metody.
     def __init__(self, jmeno):
         # Přiřazení parametru do atributu instance jmeno

csharp.html.markdown

@@ -160,7 +160,7 @@ on a new line! ""Wow!"", the masses cried";
             // List<datatype> <var name> = new List<datatype>();
             List<int> intList = new List<int>();
             List<string> stringList = new List<string>();
-            List<int> z = new List<int> { 9000, 1000, 1337 }; // intialize
+            List<int> z = new List<int> { 9000, 1000, 1337 }; // initialize
             // The <> are for generics - Check out the cool stuff section
 
             // Lists don't default to a value;
@@ -460,7 +460,7 @@ on a new line! ""Wow!"", the masses cried";
         {
             // OPTIONAL PARAMETERS
             MethodSignatures(3, 1, 3, "Some", "Extra", "Strings");
-            MethodSignatures(3, another: 3); // explicity set a parameter, skipping optional ones
+            MethodSignatures(3, another: 3); // explicitly set a parameter, skipping optional ones
 
             // BY REF AND OUT PARAMETERS
             int maxCount = 0, count; // ref params must have value
@@ -481,7 +481,7 @@ on a new line! ""Wow!"", the masses cried";
             // in case variable is null
             int notNullable = nullable ?? 0; // 0
             
-            // ?. is an operator for null-propogation - a shorthand way of checking for null
+            // ?. is an operator for null-propagation - a shorthand way of checking for null
             nullable?.Print(); // Use the Print() extension method if nullable isn't null
 
             // IMPLICITLY TYPED VARIABLES - you can let the compiler work out what the type is:
@@ -650,7 +650,7 @@ on a new line! ""Wow!"", the masses cried";
             {
                 return _cadence;
             }
-            set // set - define a method to set a proprety
+            set // set - define a method to set a property
             {
                 _cadence = value; // Value is the value passed in to the setter
             }

css.html.markdown

@@ -106,6 +106,20 @@ selected:link { }
 /* or an element in focus */
 selected:focus { }
 
+/* any element that is the first child of its parent */
+selector:first-child {}
+
+/* any element that is the last child of its parent */
+selector:last-child {}
+
+/* Just like pseudo classes, pseudo elements allow you to style certain parts of a document  */
+
+/* matches a virtual first child of the selected element */
+selector::before {}
+
+/* matches a virtual last child of the selected element */
+selector::after {}
+
 /* At appropriate places, an asterisk may be used as a wildcard to select every
    element */
 * { } /* all elements */

d.html.markdown

@@ -23,8 +23,10 @@ about [D](http://dlang.org/). The D programming language is a modern, general-pu
 multi-paradigm language with support for everything from low-level features to
 expressive high-level abstractions.
 
-D is actively developed by Walter Bright and Andrei Alexandrescu, two super smart, really cool
-dudes. With all that out of the way, let's look at some examples!
+D is actively developed by a large group of super-smart people and is spearheaded by
+[Walter Bright](https://en.wikipedia.org/wiki/Walter_Bright) and
+[Andrei Alexandrescu](https://en.wikipedia.org/wiki/Andrei_Alexandrescu).
+With all that out of the way, let's look at some examples!
 
 ```c
 import std.stdio;
@@ -36,9 +38,10 @@ void main() {
         writeln(i);
     }
 
-    auto n = 1; // use auto for type inferred variables
+    // 'auto' can be used for inferring types.
+    auto n = 1;
 
-    // Numeric literals can use _ as a digit seperator for clarity
+    // Numeric literals can use '_' as a digit separator for clarity.
     while(n < 10_000) {
         n += n;
     }
@@ -47,13 +50,15 @@ void main() {
         n -= (n / 2);
     } while(n > 0);
 
-    // For and while are nice, but in D-land we prefer foreach
-    // The .. creates a continuous range, excluding the end
+    // For and while are nice, but in D-land we prefer 'foreach' loops.
+    // The '..' creates a continuous range, including the first value
+    // but excluding the last.
     foreach(i; 1..1_000_000) {
         if(n % 2 == 0)
             writeln(i);
     }
 
+    // There's also 'foreach_reverse' when you want to loop backwards.
     foreach_reverse(i; 1..int.max) {
         if(n % 2 == 1) {
             writeln(i);
@@ -69,16 +74,18 @@ are passed to functions by value (i.e. copied) and classes are passed by referen
 we can use templates to parameterize all of these on both types and values!
 
 ```c
-// Here, T is a type parameter. Think <T> from C++/C#/Java
+// Here, 'T' is a type parameter. Think '<T>' from C++/C#/Java.
 struct LinkedList(T) {
     T data = null;
-    LinkedList!(T)* next; // The ! is used to instaniate a parameterized type. Again, think <T>
+
+    // Use '!' to instantiate a parameterized type. Again, think '<T>'.
+    LinkedList!(T)* next;
 }
 
 class BinTree(T) {
     T data = null;
 
-    // If there is only one template parameter, we can omit parens
+    // If there is only one template parameter, we can omit the parentheses.
     BinTree!T left;
     BinTree!T right;
 }
@@ -93,37 +100,34 @@ enum Day {
     Saturday,
 }
 
-// Use alias to create abbreviations for types
-
+// Use alias to create abbreviations for types.
 alias IntList = LinkedList!int;
 alias NumTree = BinTree!double;
 
 // We can create function templates as well!
-
 T max(T)(T a, T b) {
     if(a < b)
         return b;
 
     return a;
 }
 
-// Use the ref keyword to ensure pass by referece.
-// That is, even if a and b are value types, they
-// will always be passed by reference to swap
+// Use the ref keyword to ensure pass by reference. That is, even if 'a' and 'b'
+// are value types, they will always be passed by reference to 'swap()'.
 void swap(T)(ref T a, ref T b) {
     auto temp = a;
 
     a = b;
     b = temp;
 }
 
-// With templates, we can also parameterize on values, not just types
+// With templates, we can also parameterize on values, not just types.
 class Matrix(uint m, uint n, T = int) {
     T[m] rows;
     T[n] columns;
 }
 
-auto mat = new Matrix!(3, 3); // We've defaulted type T to int
+auto mat = new Matrix!(3, 3); // We've defaulted type 'T' to 'int'.
 
 ```
 
@@ -133,21 +137,20 @@ have the syntax of POD structures (`structure.x = 7`) with the semantics of
 getter and setter methods (`object.setX(7)`)!
 
 ```c
-// Consider a class parameterized on a types T, U
-
+// Consider a class parameterized on types 'T' & 'U'.
 class MyClass(T, U) {
     T _data;
     U _other;
-
 }
 
-// And "getter" and "setter" methods like so
+// And "getter" and "setter" methods like so:
 class MyClass(T, U) {
     T _data;
     U _other;
 
-    // Constructors are always named `this`
+    // Constructors are always named 'this'.
     this(T t, U u) {
+        // This will call the setter methods below.
         data = t;
         other = u;
     }
@@ -170,16 +173,24 @@ class MyClass(T, U) {
         _other = u;
     }
 }
-// And we use them in this manner
 
+// And we use them in this manner:
 void main() {
-    auto mc = MyClass!(int, string);
+    auto mc = new MyClass!(int, string)(7, "seven");
+
+    // Import the 'stdio' module from the standard library for writing to
+    // console (imports can be local to a scope).
+    import std.stdio;
+
+    // Call the getters to fetch the values.
+    writefln("Earlier: data = %d, str = %s", mc.data, mc.other);
 
-    mc.data = 7;
-    mc.other = "seven";
+    // Call the setters to assign new values.
+    mc.data = 8;
+    mc.other = "eight";
 
-    writeln(mc.data);
-    writeln(mc.other);
+    // Call the getters again to fetch the new values.
+    writefln("Later: data = %d, str = %s", mc.data, mc.other);
 }
 ```