Recent changes to 01_Pointers References

01_Pointers References modified by Nitin Deshpande

Nitin Deshpande — Mon, 01 Dec 2014 17:31:14 -0000

01_CPP modified by Nitin Deshpande

Nitin Deshpande — Tue, 25 Nov 2014 02:19:13 -0000

--- v6
+++ v7
@@ -75,7 +75,43 @@
 - C: <TYPE>& functionname(param1,param2,...,paramN) returns an object of type <TYPE>
 }

+C[3]:
+{
+C: Stream Class Shift Operators "<<" and ">>"
+C: << returns reference to cout object.
+C: >> returns reference to cin object.
+}
+
+C[4]:
+{
+C: Assignment Operator =
+The assignment operator '=' returns a reference to the lvalue (operand on the left of the '='). The lvalue must therefore be an object.
+}
+
+C[5]:
+{
+_**Pointers**_
+C: A Pointer is an expression that contains the data and address of another object. The & operator provides the address to an int object, and pointer to a declared object.
+C: A pointer points to an address of an object.
+C: Pointer variables can store address of another object. Init details int* ptr or int *ptr ( read as ptr is a pointer to type int, * to be read as pointer to).
+C: Declare a pointer of type T, T* ptrName;, next, point the pointer at a memory address (of a variable that belongs to the same base class as ptrName, i.e T.) of another variable.
+   T varName; ptrName = &varName;
+
+_**Pointers vs References**_
+C: A pointer is not merely an alias. However, both references and pointers refer to an object in memory.
+C: A pointer has a separate identity of its own. It has its address. T* ptrName; &ptrName would provide the address of the pointer ptrName.
+C: A reference on the other hand cannot be manipulated. In contrast to a reference, a pointer can be manipulated by pointing it to a new address in memory.
+
+_**The Dereferencing operator * or Indirection operator**_
+C: The * operator facilitates by providing the “value pointed by” a pointer ptrname.
+}
+
+C[6]:
+{
+_**Pointers as function parameters**_
+C: A way of passing the address of the object as a function parameter.
+C: This can be acheived by declaring a pointer variable.
+}
+
 Nitin Deshpande
 <deshpand@in.tum.de>
-
-

01_CPP modified by Nitin Deshpande

Nitin Deshpande — Tue, 25 Nov 2014 00:28:53 -0000

--- v5
+++ v6
@@ -64,7 +64,7 @@
 cout<< "name contains: "<< name << endl;
 =======================================================================================================

-Functions that return reference.
+_**Functions that return reference.**_
 C[2]:
 {
 - C: <TYPE>& functionname(param1,param2,...,paramN)
@@ -79,4 +79,3 @@
 <deshpand@in.tum.de>

-

01_CPP modified by Nitin Deshpande

Nitin Deshpande — Mon, 24 Nov 2014 20:31:58 -0000

01_CPP modified by Nitin Deshpande

Nitin Deshpande — Mon, 24 Nov 2014 20:31:28 -0000

--- v3
+++ v4
@@ -39,10 +39,44 @@
 - C: The reference &refT is a different way to express T. Operations such as refT++, refT--, refT*=4 affect the value of T.
 - C: The reference & occurs only in the declaration/inits.
 }
+=======================================================================================================
+<http: www.cplusplus.com="" reference="" string="" string="" getline=""/>
+std::getline (string)
+(1)    
+istream& getline (istream&  is, string& str, char delim);
+istream& getline (istream&& is, string& str, char delim);
+(2)    
+istream& getline (istream&  is, string& str);
+istream& getline (istream&& is, string& str);
+=======================================================================================================
+Parameters
+is
+istream object from which characters are extracted.
+str
+string object where the extracted line is stored.
+The contents in the string before the call (if any) are discarded and replaced by the extracted line.
+=======================================================================================================
+Return Value
+The same as parameter is.
+=======================================================================================================
+cout<< "Enter the name, once done, hit Enter..." << endl;
+getline(cin,name); //http://www.cplusplus.com/reference/string/string/getline/
+cout<< "name contains: "<< name << endl;
+=======================================================================================================
+
+Functions that return reference.
+C[2]:
+{
+- C: <TYPE>& functionname(param1,param2,...,paramN)
+eg: float& floorval(float floatVal) returns the floor value of a float value number. For instance, floorval(4.98) would return 4.0F.
+- C: Some operation performed on the function would effect the return value and not the parameters. ++floorval(4.98) would return 5.0F.
+- C: Returning ref from a function vs normal functions - In the latter case, you cannot perform any operations on the return values of the function call, but in the former case it
+is possible. For eg: float floorval(float floatVal), this operation during function call ++floorval(1.0,4.0) is not possible.
+- C: <TYPE>& functionname(param1,param2,...,paramN) returns an object of type <TYPE>
+}

 Nitin Deshpande
 <deshpand@in.tum.de>

-

01_CPP modified by Nitin Deshpande

Nitin Deshpande — Mon, 24 Nov 2014 12:23:04 -0000

--- v2
+++ v3
@@ -14,7 +14,7 @@
 * Return values as references from functions?
 * Pass by ref vs pass by value...

-**MAIN:**
+MAIN:
 A reference is a mere alias for an existing object. Meaning, it would store the address of a variable.

@@ -29,6 +29,9 @@
 int h=10;  
 float &p=h;

+* C: Underneath it all, a reference refT to object T is typically the machine address of the object T.
+
+* C: In compiler writer lingo, a reference is an "lvalue" (something that can appear on the left hand side of an assignment operator).

 C[1]:
 {
@@ -43,4 +46,3 @@

-

01_CPP modified by Nitin Deshpande

Nitin Deshpande — Mon, 24 Nov 2014 11:00:43 -0000

--- v1
+++ v2
@@ -37,7 +37,6 @@
 - C: The reference & occurs only in the declaration/inits.
 }

-Author
 Nitin Deshpande
 <deshpand@in.tum.de>

01_CPP modified by Nitin Deshpande

Nitin Deshpande — Mon, 24 Nov 2014 10:56:00 -0000

01 Pointers and references

This readme would contain notes and practical aspects from
[CGCPP] A_Complete_Guide_to_Programming_in_C++_Ulla_Kirch_Prinz_Peter_Prinz
[ISCPP] Industrial_Strength_C++_Henricson_Nyquist
C[<number>]: Important concepts
C: Concept
MAIN: Main objective / Introductory notes.

[CGCPP]: References and pointers
Objectives of the chapter:
MAIN: What is a pointer and what is a reference?
How to pass references as parameters to functions?
Return values as references from functions?
* Pass by ref vs pass by value...

MAIN:
A reference is a mere alias for an existing object. Meaning, it would store the address of a variable.

C: A reference value has to be initialised in the code. If not, trash values can occur, or the compiler will generate
an error message.
C: Once initialised, it is unchangeable. Meaning, in the subsequent lines of codes, you cannot use the reference to address a different variable.
C: & is used to define a reference to a datatype. for eg: float &p; is read as reference to type float.
C: Reference provided to an object should be of the same type. Meaning, the following lines of code will not compile:
int h=10;
float &p=h;

C[1]:
{
- C: Do not confuse with the address operator "&".... this merely returns the address of the object.
- C: The reference &refT is a different way to express T. Operations such as refT++, refT--, refT*=4 affect the value of T.
- C: The reference & occurs only in the declaration/inits.
}

Author
Nitin Deshpande
deshpand@in.tum.de