Handling Data Types in Mixed-Language Programming Overview

Even when you have reconciled calling conventions, naming conventions, and methods of data exchange, you must still be concerned with data types, because each language handles them differently.

The following table lists the equivalent data types between Fortran and C:

Equivalent Data Types

Fortran Data Type	C Data Type
INTEGER(1)	char
INTEGER(2)	short
INTEGER(4)	int, long
INTEGER(8)	_int64
REAL(4)	float
REAL(8)	double
REAL(16)	---
CHARACTER(1)	unsigned char
CHARACTER()	See Handling Character Strings
COMPLEX(4)	struct complex4 { float real, imag; };
COMPLEX(8)	struct complex8 { double real, imag; };
COMPLEX(16)	---
All LOGICAL types	Use integer types for C

See these topics:

Handling Numeric, Complex, and Logical Data Types

Handling Fortran Array Pointers and Allocatable Arrays

Handling Intel Fortran Pointers

Handling Arrays and Fortran Array Descriptors

Handling Character Strings

Handling User-Defined Types