You need to account for corresponding data types in Fortran and C when passing data from one language to another.
The Corresponding data types in Fortran and C table shows the data types available in the XL Fortran and C languages. Further topics detail how Fortran arguments can be passed by reference to C programs. To use the Fortran 2003 Standard interoperability features, see the BIND attribute and ISO_C_BINDING module .