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--- embedded:c [2025/08/31 09:01] – [VARIABLES] v1ctor
+++ embedded:c [2026/03/06 13:16] (current) – [VARIABLES] v1ctor
@@ Line 4: / Line 4: @@
   * **char** - 1 byte - is used to store a single character (ASCII) value
-  * Various **int**'s
+<code c>
+char Temp;    // Variable definition or declaration (letting compiler know we will need it in the future)
+Temp = 25;    // Variable initialisation (assigning a value)
+extern int my_var // Declaration. It tells the compiler that my_var is defined outside this file
+</code>
+**Address of the variable**
+<code c>
+char a1 = 'A';
+&a1                 // Gives you an address - memory location of the variable temp. Type is char*
+printf("%p\n", &a1) // %p - is the special format specifier for pointers
+</code>
+**Storage Class** of the variable defines:
+  * Scope of the variable
+  * Visibility of the variable
+  * Life time of the variable
+**static** - creates global variable but private to the specific function.
+<code c>
+void myFunc(void)
+{
+  static int count = 0;
+  count = count + 1;
+  printf("Function was called %d times\n", count);
+}
+</code>
+Another use case for **static** - prevent access to the global variables from another files:
+<code c>
+static int internal_global_var; // Won't be accessible outside this file, even with extern
+</code>
+**extern** - is used to access the global variable, which is defined outside the scope of a file
+**ASCII**
+<code c>
+  char a1 = 'A'; // Compiler replaces 'A' with 65 and stores it in a1
+  char a2 = 65;  // basically the same as initialising it with 'A'
+  printf("%c\n", a1); // prints 'A'
+  printf("%c\n", a2); // prints also 'A'
+</code>
+==== PRINTF FORMATTERS ====
+  * %u - unsigned
+  * %lf - double
+  * %f - float
+  * %le, %e - real number in the scientific representation
+  * %#x - hexadecimal with a leading 0x
+  * %s - string
+==== ASCII ==
+<code c>
+char a1 = 'A'; // Compiler will replace 'A' with 65
+</code>
+If an arithmetic operator has one floating-point operand and one integer operand, however, the integer will be converted to floating point before the operation is done.
+==== PRECEDENCE ====
+  - !=
+  - =
+==== LOGICAL OPERATORS ====
+  * && - AND
+  * || - OR
+  * ! - NOT
+**True** is anything but 0, e.g.
+<code c>
+uint8_t a = 4;
+uint8_t b = 8;
+uint8_t c = 0;
+c = a && b; // c == 1
+</code>
+==== BITWISE OPERATORS ====
+  * & - bitwise AND (usually used to test or clear bits)
+  * | - bitwise OR (usually used to set bits)
+  * ~ - bitwise NOT (unary operator, usually used to clear bits)
+  * ^ - XOR (usually used to toggle bits)
+<code c>
+a = ~c; // bitwise unary NOT
+</code>
+==== BITWISE SHIFT ===
+  * >> - a value will be divided by 2 for each right shift
+  * << - a value will be multiplied by 2 for each left shift
+Example clearing the 4th bit with a bitwise shift operator and negation:
+<code c>
+data = data &~(1<<4);
+</code>
+Example bit extraction for bits [14:9]. The algorithm:
+  - Shift the portion to the right, until it touches the LSB
+  - Mask the value to extract only 6 bits [5:0]
+<code c>
+data = data >> 9;
+data &=63;
+</code>
+==== LOOPING ====
+WHILE
+<code c>
+while(expression) // repeat execution of code inside the loop body until expression evaluates to 0
+{
+    statemen1;
+}
+</code>