CODEWITHSUNDEEP
fortran
Kittu
Kittu

Reputation: 325

equivalence statements in fortran

I am porting application from fortran to JAVA.I was wondering how to convert if equivalence is between two different datatypes.

If I type cast,i may loose the data or should I pass that as byte array?

Upvotes: 2

Views: 3374

Answers (2)

M. S. B.
M. S. B.

Reputation: 29391

You have to fully understand the old FORTRAN code. EQUIVALENCE shares memory WITHOUT converting the values between different datatypes. Perhaps the programmer was conserving memory by overlapping arrays that weren't used at the same time and the EQUIVALENCE can be ignored. Perhaps they were doing something very tricky, based on the binary representation of a particular platform, and you will need to figure out what they were doing.

There is extremely little reason to use EQUIVALENCE in modern Fortran. In most cases where bits need to be transferred from one type to another without conversion, the TRANSFER intrinsic function should be used instead.

Upvotes: 3

tpg2114
tpg2114

Reputation: 15100

From http://www.fortran.com/F77_std/rjcnf0001-sh-8.html#sh-8.2 :

An EQUIVALENCE statement is used to specify the sharing of storage units by two or more entities in a program unit. This causes association of the entities that share the storage units.

If the equivalenced entities are of different data types, the EQUIVALENCE statement does not cause type conversion or imply mathematical equivalence. If a variable and an array are equivalenced, the variable does not have array properties and the array does not have the properties of a variable.

So, consider the reason it was EQUIVALENCE'd in the Fortran code and decide from there how to proceed. There's not enough information in your question to assess the intention or best way to convert it.

Upvotes: 2

Related Questions