Databases
StackOverflow2013
Postsdbo
POHow can I call a C function expecting an array of structs from Java using swig?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow can I call a C function expecting an array of structs from Java using swig?
    primarykey
    data
    text
    <p>I have a C function that takes an array of structures as an argument, and I want to call this function from Java by way of SWIG, but the documentation seems quite murky on this subject and I can't find any stackoverflow questions that directly address this case. Here is an example that is similar to what I want to do:</p> <p>C header file:</p> <pre><code>typedef struct { int timeToPayment; double paymentAmount; } Payment; double presentValue(Payment *payments, int nPayments); </code></pre> <p>Java code snippet:</p> <pre><code>... Class Payment { public int timeToPayment; public double paymentAmount; }; ... Payment[] payments = new Payment[3]; payments[0].timeToPayment = 30; payments[0].paymentAmount = 1.0; payments[1].timeToPayment = 60; payments[1].paymentAmount = 2.0; payments[2].timeToPayment = 90; payments[2].paymentAmount = 3.0; double pv = CLIBRARY.presentValue(payments); // also acceptable: double pv = CLIBRARY.presentValue(payments, payments.length); </code></pre> <p>How can this be accomplished?</p> <p>EDIT: to provide additional information, SWIG is a requirement because it is already used to incorporate simpler interfaces into the same Java codebase and supporting more than one approach for solving this problem will not be acceptable. Also, the signature of the C functions can't be changed and this example has been extremely simplified; the actual problem involves multiple C functions with signatures requiring arrays of structs (multiple arrays of different structs in some cases) and some of the structs are quite large, so I would really, really prefer not to have to break them up into equivalent arrays of primitive types.</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USBD at Rivenhill
    1. USBD at Rivenhill
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COI'd suggest using carrays.i for this if at all possible - it's not a "proper" Java array, but it's efficient for both input and output. It would be possible to write a more complicated typemap that does this, but it would be quite cumbersome for every function call. Can you change the signature of the C function at all?
      singulars
      1. POHow can I call a C function expecting an array of structs from Java using swig?
      1. USFlexo
    2. CO@Flexo - can't change the C function signatures and would prefer not to write wrappers for them, see my edit for explanation. Thanks for helping me clarify the requirements.
      singulars
      1. POHow can I call a C function expecting an array of structs from Java using swig?
      1. USBD at Rivenhill
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload