Couldn't understand what my error means

[blackx]

I got this error:

error C2664: 'Vector::setVec tor' : cannot convert parameter 1 from 'const std::ifstream' to 'std::ifstream'

How can it not be able to convert from std::ifstream to std::ifstream?? ?

Here's the relevant code (I didn't put all the variables as those are not relevant):

header file:
class Matrix{

public:
.
.
.
.

void setMatrix(ifstr eam txtFile);

};

void Matrix::setMatr ix (ifstream txtFile) {
int x;

for (int i = 0; i < this->rowLength; i++) {
for (int j = 0; j < this->columnLength ; j++) {
txtFile >> x;
this->contents[i][j] = x;
}
}
}

cpp file:

void main() {
string txtFileName;

Matrix matrix1;

cout << "Enter name of vector/matrix file (use a txt file): ";
cin >> txtFileName;

ifstream txtFile(txtFile Name.c_str());


matrix1.setMatr ix (txtFile); //error occurs here
}

[blackx]

I posted the wrong error code, here's the relevant error code:

error C2664: 'Matrix::setMat rix' : cannot convert parameter 1 from 'std::ifstream' to 'std::ifstream'
No copy constructor available for class 'std::basic_ifs tream<_Elem,_Tr aits>' or constructor attempts to perform illegal conversion to non-__gc reference
with
[
_Elem=char,
_Traits=std::ch ar_traits<char>
]

[Savage]

Have you tryed passing it with reference:

void Matrix::setMatr ix(const ifstream &txtFile);

??
PS:Please use code tags(#button)
Savage

[blackx]

thanks for replying,

if I pass by reference,

in main();

should i use:

matrix1.setMatr ix (txtFile); //there's no compile error here but the values returned are memory addresses, not the actual values

or

matrix1.setMatr ix (&txtFile); //this gives a compile error

error C2664: 'Matrix::setMat rix' : cannot convert parameter 1 from 'std::ifstream *__w64 ' to 'std::ifstream &'

[Savage]

thanks for replying,

if I pass by reference,

in main();

should i use:

matrix1.setMatr ix (txtFile); //there's no compile error here but the values returned are memory addresses, not the actual values

or

matrix1.setMatr ix (&txtFile); //this gives a compile error

error C2664: 'Matrix::setMat rix' : cannot convert parameter 1 from 'std::ifstream *__w64 ' to 'std::ifstream &'

There is no difference in function call when your function takes a pass by reference and pass by value.The problem is somewhere else.

How did you found that return values are memory addresses?

Savage

[blackx]

using

matrix1.setMatr ix (txtFile);

I run the code and got like -85988360 as values in my matrix (must be memory addresses)

any suggestions on how to fix my code?

[Savage]

using

matrix1.setMatr ix (txtFile);

I run the code and got like -85988360 as values in my matrix (must be memory addresses)

any suggestions on how to fix my code?

Try couting x from inside the setMatrix() function.

Savage

[blackx]

I actually have a different function, printMatrix() that does the cout. But I will try to include the cout inside the setMatrix function and see what I get.

[Savage]

I actually have a different function, printMatrix() that does the cout. But I will try to include the cout inside the setMatrix function and see what I get.

It's only for debug purposes.

Savage

[blackx]

okay something is definitely wrong with my code, I tried 2 different methods of reading.

the txt file reads:

1.0 2.0 3.6 4.0

1 2 3 4
2 3 4 5
3 4 5 6
4 5 6 7

1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1

but when I run the code (with the cout inside the setVector and setMatrix functions), I got
Vector:
1.0000 1.0000 1.0000 1.0000

Matrix:
1.0000 1.0000 1.0000 1.0000
1.0000 1.0000 1.0000 1.0000
1.0000 1.0000 1.0000 1.0000
1.0000 1.0000 1.0000 1.0000

Here's the code for the function:

method 1

void Vector::setVector (string txtFileName) {
    int x;
 
    ifstream txtFile(txtFileName.c_str());
 
    for (int i = 0; i < this->length; i++) {
        txtFile >> x;
        this->contents[i] = x;            
    }
 
    int numberWidth = 8;
    int decimalPlaces = 4;
 
    for (int i = 0; i < this->length; i++) {
        cout.width(numberWidth); 
        cout << fixed << setprecision(decimalPlaces) << this->contents[i];
        cout << '\t';
    }
 
    cout << endl;
} 

method 2:

void Matrix::setMatrix (ifstream &txtFile) {
    int x;
 
    for (int i = 0; i < this->rowLength; i++) {
        for (int j = 0; j < this->columnLength; j++) {
            txtFile >> x;
            this->contents[i][j] = x;            
        }
    }
 
    int numberWidth = 8;
    int decimalPlaces = 4;
 
    for (int i = 0; i < this->rowLength; i++) {
        for (int j = 0; j < this->columnLength;  j++) {
            cout.width(numberWidth); 
            cout << fixed << setprecision(decimalPlaces) << this->contents[i][j];
            cout << '\t';
        }
        cout << endl; 
    }
 
    cout << endl;
}