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Created page containing Sept 24 2010 OOP344 Typewithme notes
== Pointers ==
* address
*: beginning of location in memory
*: just an unsigned integer but adding one to a pointer, adds the size of the target to the pointer
* sizeof(pointer) is always the same regardless of the type of the targer of the pointer
== Declaration of Pointers ==
* int* p, not int *p (integer pointer variable named p, not integer variable of pointer named p)
* undefined pointer points to "garbage"
== Int vs. pointer ==
* int can be signed (positive / negative)
* pointers are unsigned (only positive) and adding one to a pointer, adds the size of the target to the pointer
== Use of pointers ==
* &a = "address of variable a"
* *p = "where p is pointing to" OR "data at pointer p"
* int* p = 8; (pointer p is now pointing to memory location 8)
* if p is an int pointer variable, p++ will increment the address of p by the memory size of an int (so p will be 12)
== Arrays ==
* 'int a[5];' creates 6 objects.... 5 integers and 1 pointer
* *a is the same as a[0]
* string = array of characters terminated by a null character
* Dereferencing operator (*) takes precendence over +/- operators (Quiz alert)
* Using 'int a[5] = {10, 20, 30, 40, 50};', *a would point to the beginning of the array, where the value '10' is located
* '*a+2' first resolves data at a, and then adds 2, giving us '12'
* '*(a+2)' gives us the data 2 integers 'forward' from the beginning of the array 'a'
* With two-dimensional arrays, 'a' will point to a 'pack', or 'row', of integers. (a + 1) will move to the next pack, or row, of integers.
* Multi-dimensional arrays are actually represented as single-dimension arrays within the system memory.
== Lazy Evaluation ==
* When evaluating numerous condition statements connected with && (AND), the moment a "false" is encountered, no further statements are evaluated, because the statement as a whole is false.
* A method of substituting if statements by using && (AND) operand.
* Pseudocode : (boolean statement) && (action performed if boolean statement is true)
* Lazy Evaluation is generally faster than if statements.
== Misc ==
sizeof(int); = operator that returns the memory size of data type given as argument. in this case, it returns the size of an int. can also operate on objects.
== Credits ==
Notes taken by [[User:dkarp | Dale Karp ]] and [[User:dslessarev | Daniel Slessarev ]]
* address
*: beginning of location in memory
*: just an unsigned integer but adding one to a pointer, adds the size of the target to the pointer
* sizeof(pointer) is always the same regardless of the type of the targer of the pointer
== Declaration of Pointers ==
* int* p, not int *p (integer pointer variable named p, not integer variable of pointer named p)
* undefined pointer points to "garbage"
== Int vs. pointer ==
* int can be signed (positive / negative)
* pointers are unsigned (only positive) and adding one to a pointer, adds the size of the target to the pointer
== Use of pointers ==
* &a = "address of variable a"
* *p = "where p is pointing to" OR "data at pointer p"
* int* p = 8; (pointer p is now pointing to memory location 8)
* if p is an int pointer variable, p++ will increment the address of p by the memory size of an int (so p will be 12)
== Arrays ==
* 'int a[5];' creates 6 objects.... 5 integers and 1 pointer
* *a is the same as a[0]
* string = array of characters terminated by a null character
* Dereferencing operator (*) takes precendence over +/- operators (Quiz alert)
* Using 'int a[5] = {10, 20, 30, 40, 50};', *a would point to the beginning of the array, where the value '10' is located
* '*a+2' first resolves data at a, and then adds 2, giving us '12'
* '*(a+2)' gives us the data 2 integers 'forward' from the beginning of the array 'a'
* With two-dimensional arrays, 'a' will point to a 'pack', or 'row', of integers. (a + 1) will move to the next pack, or row, of integers.
* Multi-dimensional arrays are actually represented as single-dimension arrays within the system memory.
== Lazy Evaluation ==
* When evaluating numerous condition statements connected with && (AND), the moment a "false" is encountered, no further statements are evaluated, because the statement as a whole is false.
* A method of substituting if statements by using && (AND) operand.
* Pseudocode : (boolean statement) && (action performed if boolean statement is true)
* Lazy Evaluation is generally faster than if statements.
== Misc ==
sizeof(int); = operator that returns the memory size of data type given as argument. in this case, it returns the size of an int. can also operate on objects.
== Credits ==
Notes taken by [[User:dkarp | Dale Karp ]] and [[User:dslessarev | Daniel Slessarev ]]
