determining if string is valid numerical type

[tracyx]

I have a string that I want to convert into a numerical type (integer or real). Is there an elegant way to determine whether the string contains a valid numerical type, or is it necessary to loop over all the characters to determine this?

Thanks, Tracy

[anthonyrichards]

Quoting - tracyx

I have a string that I want to convert into a numerical type (integer or real). Is there an elegant way to determine whether the string contains a valid numerical type, or is it necessary to loop over all the characters to determine this?

Thanks, Tracy

Use internal READ and use ERR= branching until you get no error. e.g.

READ(STRING,ERR=9999, *) realvariable
READ(STRING,ERR=9999, *) integervariable

[Steven_L_Intel1 · Accepted solution]

Quoting - anthonyrichards

Use internal READ and use ERR= branching until you get no error. e.g.

READ(STRING,ERR=9999, *) realvariable
READ(STRING,ERR=9999, *) integervariable

Perhaps you meant READ(STRING,*,ERR=9999)? In any event, I do not recommend using list-directed reads for doing input validation. It is much more liberal about what it will consider valid input than is wanted here. For example, it will accept a comma or a slash. I would suggest an explicit format with an In or Gn.0 format as needed, where n is the width of the string.

[tracyx]

Quoting - Steve Lionel (Intel)

Perhaps you meant READ(STRING,*,ERR=9999)? In any event, I do not recommend using list-directed reads for doing input validation. It is much more liberal about what it will consider valid input than is wanted here. For example, it will accept a comma or a slash. I would suggest an explicit format with an In or Gn.0 format as needed, where n is the width of the string.

Thank you both, that is perfect for my needs.

Kind regards, Tracy

[jimdempseyatthecove]

Tracy,

In your debug build, consider not only using the Gn.0 or other format specifier, but also include your own sanity check for spurious input. Then throw everything imagineable at the routine for testing. A false positive is not an indication that the data is correct. And, remember actual input data may be stranger than you can imagine.

Jim Dempsey

[rase]

John Burkardt maintains various libraries with Fortran source code, among them one called CHRPAK with routines for conversion of character strings and other string-related functions (http://people.sc.fsu.edu/~burkardt/f_src/chrpak/chrpak.html) . Maybe you can find there what you are looking for.