How to read matrix from text file in C++

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Dear All,
I have some matrix written in text file and I want to store these matrices in 2 d integer array.I have tried to read it using getline but it reads the whole line.How can I read from specific location in text file.Size of matrices is also unknown.

My text file is like

Matrix A is

2 4 8 10 2
1 2 5 7 11

Matrix B is
1 2 3
11 25 27

It would be really nice,if anyone body can help me.

Regards,
Ishtiaq

Posted 12-Jun-11 12:42pm

smishtiaqhussain

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Sergey Alexandrovich Kryukov 12-Jun-11 21:10pm

If a size of matrix is unknown, can number of rows also change? If so, what defines the number of rows? Not clear. Otherwise, it's a trivial problem.
--SA

smishtiaqhussain 13-Jun-11 13:02pm

thanks for reply.......its done

Sandeep Mewara 13-Jun-11 10:45am

Any effort?

smishtiaqhussain 13-Jun-11 13:01pm

thanks ......its done just now.

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Albert Holguin · Accepted Answer · 2011-06-12T16:47:00

As the name of getline() implies, it's used for reading entire lines at a time... if you want to read an integer at a time... try this:

ifstream file;
file.open( "C:\\TestFile.txt");
int test[5] = {0};

for( int i=0; i<5; i++)
    file >> test[i];

file.close();

Now for this code I just read in 5 numbers into a flat 1D array, but that should give you the right idea of what you need to do. If you need it to be dynamic, you'll have to allocate the array dynamically:

int *test; //declare as pointer
test = new int[size]; //Allocate after you figure out the size

//After you're done with it, deallocate
delete [] test;