A significant number of applications use C, C++, and Fortran together, by calling each other or sharing files. It is currently easier to modify data sizes and types on the C side than the on Fortran side of such applications. The following table lists C and C++ types and the equivalent Fortran types in the different modes.
| C/C++ type | Fortran type | |
|---|---|---|
| 32-bit | 64-bit | |
| signed int | INTEGER | INTEGER |
| signed long | INTEGER | INTEGER*8 |
| unsigned long | LOGICAL | LOGICAL*8 |
| pointer | INTEGER | INTEGER*8 |
| integer POINTER (8 bytes) | ||