Couldn't understand what my error means

[blackx]

I got this error:

error C2664: 'Vector::setVector' : 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(ifstream txtFile);

};

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;
}
}
}

cpp file:

void main() {
string txtFileName;

Matrix matrix1;

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

ifstream txtFile(txtFileName.c_str());


matrix1.setMatrix (txtFile); //error occurs here
}

[blackx]

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

error C2664: 'Matrix::setMatrix' : cannot convert parameter 1 from 'std::ifstream' to 'std::ifstream'
No copy constructor available for class 'std::basic_ifstream<_Elem,_Traits>' or constructor attempts to perform illegal conversion to non-__gc reference
with
[
_Elem=char,
_Traits=std::char_traits<char>
]

[Savage]

Have you tryed passing it with reference:

void Matrix::setMatrix(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.setMatrix (txtFile); //there's no compile error here but the values returned are memory addresses, not the actual values

or

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

error C2664: 'Matrix::setMatrix' : 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.setMatrix (txtFile); //there's no compile error here but the values returned are memory addresses, not the actual values

or

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

error C2664: 'Matrix::setMatrix' : 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.setMatrix (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.setMatrix (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;
}
 

[blackx]

for the main, I have:

cout << "Enter name of vector/matrix file (testMatrix.txt): ";
    cin >> txtFileName;
 
    ifstream txtFile(txtFileName.c_str());
 
    vector1.setVector (txtFileName); 
    matrix1.setMatrix (txtFile);
 

[Savage]

for the main, I have:

cout << "Enter name of vector/matrix file (testMatrix.txt): ";
    cin >> txtFileName;
 
    ifstream txtFile(txtFileName.c_str());
 
    vector1.setVector (txtFileName); 
    matrix1.setMatrix (txtFile);
 

Perform a check to see if file is open.

Savage

[blackx]

Perform a check to see if file is open.

Savage

what do you mean by checking if a file is open. I'm opening the file with the setMatrix function.

Thanks.

[Savage]

what do you mean by checking if a file is open. I'm opening the file with the setMatrix function.

Thanks.

ifstream,has a method called IsOpen(),which checks if file has been opened and returns a bool.Perhaps your file has not been opened and you have initialized in constructor of both vector and matrix values to 1.0

Every time you open a file you should perform a chck to see if file has been opened

Savage

[blackx]

I just wrote

txtFile.is_open()

in my main...how do I make it return true or false?

I initialized my values to 0, not 1, so I don't think its because of that.

[Savage]

I just wrote

txtFile.is_open()

in my main...how do I make it return true or false?

I initialized my values to 0, not 1, so I don't think its because of that.

Just put it into if statement:

if(txtFile.is_open())

And if it isn't that try changing in your text file first value(1.0) to something else,and see if your program than prints that.

Savage

[blackx]

I changed the first number in the txt file to 2, and yes, now I get all 2s when I run the code. Any ideas what I did wrong?

[Savage]

I changed the first number in the txt file to 2, and yes, now I get all 2s when I run the code. Any ideas what I did wrong?

Wait a secound,why is x a integer when you are reading in floats?

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;.
      }

[blackx]

whoa! you're right!

I just changed x to double and I got what I wanted!

I just spent the last 3 hours trying to fix my code, and all I did wrong was I made x int instead of double! that's crazy.

Thanks for your help man, I really appreciate it.

[Savage]

whoa! you're right!

I just changed x to double and I got what I wanted!

I just spent the last 3 hours trying to fix my code, and all I did wrong was I made x int instead of double! that's crazy.

Thanks for your help man, I really appreciate it.

I'm more than happy to help you.

I think that when x was int stream became corrupted and started to continuously throw in same value.

Savage

[blackx]

I'm more than happy to help you.

I think that when x was int stream became corrupted and started to continuously throw in same value.

Savage

that makes sense. Thanks again.

[Savage]

that makes sense. Thanks again.

Well,that's it then.

If you face another problem with these two classes,feel free to post again.

Savage