diff --git a/content/notes/10-intro-to-c-arrays-malloc-free.md b/content/notes/10-intro-to-c-arrays-malloc-free.md
index 90f453a16..82325ad67 100644
--- a/content/notes/10-intro-to-c-arrays-malloc-free.md
+++ b/content/notes/10-intro-to-c-arrays-malloc-free.md
@@ -11,6 +11,8 @@ tags:
 ``` c
 uint32_t array[10];
 float matrix[5][6];
+double balance[5] = {1000.0, 2.0, 3.4} //last two elementes will be initalised to zero
+double balance[] = {1000.0, 2.0, 3.4} //size is calculated automatically
 ```
 
 - do not have methods
@@ -21,10 +23,32 @@ float matrix[5][6];
 	- 'H' 'e' 'l' 'l' 'o' '\0' <- sentinel value
 
 ``` c
-char *check = thing;
+//find the length of an array
+size_t strlen(const char *of){
+	char *check = of;
+	
+	while(*check != '\0')
+		check++;
+	
+	return check - of;
+}
+```
 
-while(*check != '\0')
-	check++
+# quoted strings
+- "Hello World"
+- must be const - not allowed to change them
+	- `const char *hello_world = "hello world"`
+- can use then in place of char arrays
+
+# Memory
+when we decalre an array we are saying "choose somewhere in memory to put this number of that and call it thing"
+
+```c
+that thing[this];
+
+uint_t byte_array[1024];
+```
+
+- compiler chooses somewhere in memory
+- the name of the array maps to the location
 
-length = check - thing
-```
\ No newline at end of file