Thread: Lvalue required --compile error--

  1. #1
    Registered User
    Join Date
    May 2006

    Lvalue required --compile error--

    my source code is that:

    class Matrixes
    long double **data;
    public :
    Matrixes(int row,int column);
    long double** Matrixes::get();
    Matrixes::Matrixes(int row,int column)
    data = new long double*[row];
    for (int j = 0; j < row; j++)
    data[j] = new long double[column];
    long double** Matrixes::get()
    class Operations
    long double** accumulate(long double **dataC,long double **dataA,long double **dataB,int row,int column)
    Matrixes m1(3,4); // dimension of m1 object memory allocation
    m1.get()=dataA; // (1) ---------COMPILE ERROR---------
    .// function code
    in (1) line i have came across "Lvalue required"
    what does it means?
    what can i solve this problem

  2. #2
    The superhaterodyne twomers's Avatar
    Join Date
    Dec 2005
    You trying to dynamically allocate a 2D Array? try this:

    	char **X = new char*[cols];
    	*X = new char [rows];
    	for	( int i=0; i<rows; i++ )
    		for ( int j=0; j<cols; j++ )
    			X[i][j] = '*';
    			cout<< ends << X[i][j];
    		cout<< endl;
    but just change the chars to doubles. Cols and Rows are parameters the user has inputted.
    Last edited by twomers; 05-19-2006 at 07:12 AM. Reason: Forgot to explaing things

  3. #3
    ... arjunajay's Avatar
    Join Date
    May 2005
    A function cannot be put on the left hand side of an '=' expression unless it returns a 'reference'. ???
    int& max(int &a, int &b){  //this function can be put as it returns 'int &'
       return (a>b)? a : b;
    PS: this is just a quick code... I have NOT tested it...

    LVALUE is just a fancy name for things that can be put on the left hand side.
    temporary objects like the double** you returned are NOT lvalue ???
    Last edited by arjunajay; 05-19-2006 at 07:42 PM.

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