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bzsubsect(Output formatting)
bzindex(persistence)
bzindex(Array!persistence)
bzindex(output formatting)
bzindex(Array!output formatting)
bzindex(saving arrays)
bzindex(writing arrays to output streams)
bzindex(Array!saving to output stream)
bzindex(Array!writing to output stream)
The current version of Blitz++ includes rudimentary output formatting
for arrays. Here's an example:
bzexample(\
#include <blitz/array.h>
using namespace blitz;
int main()
{
Array<int,2> A(4,5,FortranArray<2>());
firstIndex i;
secondIndex j;
A = 10*i + j;
cout << "A = " << A << endl;
Array<float,1> B(20);
B = exp(-i/100.);
cout << "B = " << endl << B << endl;
return 0;
})
And the output:
bzexample(\
A = 4 x 5
[ 11 12 13 14 15
21 22 23 24 25
31 32 33 34 35
41 42 43 44 45 ]
B = 20
[ 1 0.99005 0.980199 0.970446 0.960789 0.951229 0.941765
0.932394 0.923116 0.913931 0.904837 0.895834 0.88692 0.878095
0.869358 0.860708 0.852144 0.843665 0.83527 0.826959 ]
)
bzsubsect(Inputting arrays)
bzindex(inputting arrays from an input stream)
bzindex(Array!inputting from istream)
bzindex(restoring arrays from an input stream)
bzindex(Array!restoring from istream)
Arrays may be restored from an istream using the tt(>>) operator.
bf(Note:) you must know the dimensionality of the array being
restored from the stream. The tt(>>) operator expects an
array in the same input format as generated by the tt(<<) operator,
namely:
bzindex(Array!persistence format)
startit()
it() The size of the array, for example "32" for a 1-dimensional
array of 32 elements, "12 x 64 x 128" for a 3-dimensional array
of size 12x64x128.
it() The symbol tt('[') indicating the start of the array data
it() The array elements, listed in memory storage order
it() The symbol tt(']') indicating the end of the array data
endit()
The operator prototype is:
verb(
template<class T, int N>
istream& operator>>(istream&, Array<T,N>&);
)
Here is an example of saving and restoring arrays from files.
You can find this example in the Blitz++ distribution as
tt(examples/io.cpp).
bzexample(
#include <blitz/array.h>
#include <fstream.h>
BZ_USING_NAMESPACE(blitz)
const char* filename = "io.data";
void write_arrays()
{
ofstream ofs(filename);
if (ofs.bad())
{
cerr << "Unable to write to file: " << filename << endl;
exit(1);
}
Array<float,3> A(3,4,5);
A = 111 + tensor::i + 10 * tensor::j + 100 * tensor::k;
ofs << A << endl;
Array<float,2> B(3,4);
B = 11 + tensor::i + 10 * tensor::j;
ofs << B << endl;
Array<float,1> C(4);
C = 1 + tensor::i;
ofs << C << endl;
}
int main()
{
write_arrays();
ifstream ifs(filename);
if (ifs.bad())
{
cerr << "Unable to open file: " << filename << endl;
exit(1);
}
Array<float,3> A;
Array<float,2> B;
Array<float,1> C;
ifs >> A >> B >> C;
cout << "Arrays restored from file: " << A << B << C << endl;
return 0;
}
)
bf(Note:) The storage order and starting indices are not restored
from the input stream. If you are restoring (for example) a
Fortran-style array, you must create a Fortran-style array, and
then restore it. For example, this code restores a Fortran-style
array from the standard input stream:
verb(
Array<float,2> B(fortranArray);
cin >> B;
)
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