Solved

warning C4270

Posted on 1997-06-02
3
190 Views
Last Modified: 2010-04-10
warning C4270: 'initializing' : do not initialize a non-const 'class ::String __near &' with a non-lvalue 'class ::String ' function return

This is my first test question.
I would like to know if this is a legitimate warning of if it is a bug in the compiler(MS C++ 1.52).

in book Teach Yourself C++ in 21 days ( Perry)
   there is a reference that it is a bug.
   (sorry i dont know the page)

here is the statement that gives the warning.    
    *m_pName = setName();  : warning C4270 etc.

the relevant declarations are
    String * m_pName;
    String setName();
 
the definition is

String Column::setName()
{
   String ans="dummy";
   return ans;
}

looking at the statement
   *m_pName = setName();

The String pointed to by *m_pName calls it's  operator= and copies in the contents of the String in setName(). This is precisely what I want it to do and cannot  see why the compiler has any justification for complaining.
0
Comment
Question by:cgardner
3 Comments
 
LVL 11

Expert Comment

by:mikeblas
ID: 1163794
To get an accurate answer, you'll need to show the definition and declaration of operator=() in the String class you wrote.

.B ekiM
0
 
LVL 5

Accepted Solution

by:
yonat earned 50 total points
ID: 1163795
The declaration
String * m_pName;
will definetily cause problems, since you don't set memory space
for the String pointed by m_pName. In other words, m_pName does
not point to a valid String. Instead, use
String * m_pName = new String;
or just plain old
String m_Name;
If you use the latter, then m_Name = setName() should work.
But, like mikeblass said, it depends on the definition of
String::operator=(const String&). Form the warning, I suspect
that it is wrongly declared String::operator=(String&) - without
the const.
0
 

Author Comment

by:cgardner
ID: 1163796
Thanks, your right.. I forgot the const in operator =
which caused the C4270

also I forgot to initialize..  Bonus


 

0

Featured Post

Master Your Team's Linux and Cloud Stack

Come see why top tech companies like Mailchimp and Media Temple use Linux Academy to build their employee training programs.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Container Orchestration platforms empower organizations to scale their apps at an exceptional rate. This is the reason numerous innovation-driven companies are moving apps to an appropriated datacenter wide platform that empowers them to scale at a …
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
The viewer will learn how to pass data into a function in C++. This is one step further in using functions. Instead of only printing text onto the console, the function will be able to perform calculations with argumentents given by the user.
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question