C++ Fortran Format

This is an under development module that provides a printfor function similar to Fortran's print function, with a format specification string:

printfor("(I3, SP, 2(1X, F5.2), 2X, SS, G9.3E3)", 10, 3.1416, 3.333, 2.7545E-12);
//output: 
// 10 +3.14 +3.33  .275E-011

The goal for this project is to offer C++ programmers a way to get the same output results as they would get by using FORMAT within a Fortran program.

In this version, Iw.m, Fw.d, Dw.d, Ew.d, Ew.dEe, Gw.d, Gw.dEe, Lw, A[w], SS, SP, nX, /, nH, and '' edit descriptors are supported. Both grouping () and repeat specification are supported also. See Supported Features and Known Issues for limitations. Currently, the output goes directly to the output stream (stdout) or to an user specified output stream (with std::ostream base class).

This work is inspired by py-fortranformat. Also, Acutest is used as unit testing facility.

Usage

Something like this:

program formt
implicit none
    print "(A, 2(I3, I3))", "test: ", 1, 2, 3, 4
end program formt

Becomes this:

#include "fortranformat.hpp"

void main()
{
    printfor("(A, 2(I3, I3))", "test: ", 1, 2, 3, 4);
}

Output:

test:   1  2  3  4

The printfor is also overloaded to work with any output stream based on std::ostream:

printfor(std::ostream& stream, char const* format, ...);

Supported Features

Some descriptors are fully supported (Iw.m), while others are not (such as S, TRc, kP). This means that the formatting in some cases may not reflect expected Fortran's. The following tables summarize the availability of each edit descriptor.

Some descriptors may be specified as "Recognized", where they are read from the format string but its output is basic and don't reflect expected Fortran's.

Repeatable edit descriptors

Edit Descriptor	Available?
Iw	Yes
Iw.m	Yes
Fw.d	Yes
Ew.d	Yes
Ew.dEe	Yes
Dw.d	Yes
Gw.d	Yes
Gw.dEe	Yes
Lw	Yes
A	Yes
Aw	Yes

Nonrepeatable edit descriptors

Edit Descriptor	Available?	Afftects
'h h ... h ' 1 2 n	Partial	Output
nHh h ... h 1 2 n	Partial	Output
Tc	No	Both
TLc	No	Both
TRc	No	Both
nX	Yes	Output
/	Yes	Both
:	No	Both
S	No	Output
SP	Yes	Output
SS	Yes	Output
kP	No	Both
BN	No	Input
BZ	No	Input

Known Issues

There is no check against malformed format string
Does not support escaping quotes by repeating it, such as '' or "", within nH.
Does not escape single quotation marks ' within double quotation marks strings and vice-versa.
No error is thrown when w=0.
No default values for omitted w and d.

Documentation

https://github.com/dparrini/cpp-fortranformat

Support

Feel free to report any bugs you find. You are welcome to fork and submit pull requests.

License

The module is available at GitHub under the MIT license.

dparrini / cpp-fortranformat