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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
Cgo enables the creation of Go packages that call C code.
Usage: cgo [compiler options] file.go
The compiler options are passed through uninterpreted when
invoking gcc to compile the C parts of the package.
The input file.go is a syntactically valid Go source file that imports
the pseudo-package "C" and then refers to types such as C.size_t,
variables such as C.stdout, or functions such as C.putchar.
If the import of "C" is immediately preceded by a comment, that
comment is used as a header when compiling the C parts of
the package. For example:
// #include <stdio.h>
// #include <errno.h>
import "C"
C identifiers or field names that are keywords in Go can be
accessed by prefixing them with an underscore: if x points at
a C struct with a field named "type", x._type accesses the field.
To access a struct, union, or enum type directly, prefix it with
struct_, union_, or enum_, as in C.struct_stat.
Any C function that returns a value may be called in a multiple
assignment context to retrieve both the return value and the
C errno variable as an os.Error. For example:
n, err := C.atoi("abc")
Cgo transforms the input file into four output files: two Go source
files, a C file for 6c (or 8c or 5c), and a C file for gcc.
The standard package makefile rules in Make.pkg automate the
process of using cgo. See $GOROOT/misc/cgo/stdio and
$GOROOT/misc/cgo/gmp for examples.
Cgo does not yet work with gccgo.
package documentation