## Tcl8.6.2/Tk8.6.2 Documentation > Tcl C API, version 8.6.2 > PkgRequire

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  NAME
    Tcl_PkgRequire, Tcl_PkgRequireEx, Tcl_PkgRequireProc, Tcl_PkgPresent, Tcl_PkgPresentEx, Tcl_PkgProvide, Tcl_PkgProvideEx — package version control
  SYNOPSIS
    #include <tcl.h>
    const char *
    Tcl_PkgRequire(interp, name, version, exact)
    const char *
    Tcl_PkgRequireEx(interp, name, version, exact, clientDataPtr)
    int
    Tcl_PkgRequireProc(interp, name, objc, objv, clientDataPtr)
    const char *
    Tcl_PkgPresent(interp, name, version, exact)
    const char *
    Tcl_PkgPresentEx(interp, name, version, exact, clientDataPtr)
    int
    Tcl_PkgProvide(interp, name, version)
    int
    Tcl_PkgProvideEx(interp, name, version, clientData)
  ARGUMENTS
  DESCRIPTION
  KEYWORDS
  SEE ALSO

### NAME

Tcl_PkgRequire, Tcl_PkgRequireEx, Tcl_PkgRequireProc, Tcl_PkgPresent, Tcl_PkgPresentEx, Tcl_PkgProvide, Tcl_PkgProvideEx — package version control

### SYNOPSIS

#include <tcl.h>
const char *
Tcl_PkgRequire(interp, name, version, exact)
const char *
Tcl_PkgRequireEx(interp, name, version, exact, clientDataPtr)
int
Tcl_PkgRequireProc(interp, name, objc, objv, clientDataPtr)
const char *
Tcl_PkgPresent(interp, name, version, exact)
const char *
Tcl_PkgPresentEx(interp, name, version, exact, clientDataPtr)
int
Tcl_PkgProvide(interp, name, version)
int
Tcl_PkgProvideEx(interp, name, version, clientData)

### ARGUMENTS

Tcl_Interp *interp (in)
  Interpreter where package is needed or available.

const char *name (in)
  Name of package.

const char *version (in)
  A version string consisting of one or more decimal numbers separated by dots.

int exact (in)
  Non-zero means that only the particular version specified by version is acceptable. Zero means that newer versions than version are also acceptable as long as they have the same major version number as version.

const void *clientData (in)
  Arbitrary value to be associated with the package.

void *clientDataPtr (out)
  Pointer to place to store the value associated with the matching package. It is only changed if the pointer is not NULL and the function completed successfully. The storage can be any pointer type with the same size as a void pointer.

int objc (in)
  Number of requirements.

Tcl_Obj* objv[] (in)
  Array of requirements.

### DESCRIPTION

These procedures provide C-level interfaces to Tcl's package and version management facilities.

Tcl_PkgRequire is equivalent to the package require command, Tcl_PkgPresent is equivalent to the package present command, and Tcl_PkgProvide is equivalent to the package provide command.

See the documentation for the Tcl commands for details on what these procedures do.

If Tcl_PkgPresent or Tcl_PkgRequire complete successfully they return a pointer to the version string for the version of the package that is provided in the interpreter (which may be different than version); if an error occurs they return NULL and leave an error message in the interpreter's result.

Tcl_PkgProvide returns TCL_OK if it completes successfully; if an error occurs it returns TCL_ERROR and leaves an error message in the interpreter's result.

Tcl_PkgProvideEx, Tcl_PkgPresentEx and Tcl_PkgRequireEx allow the setting and retrieving of the client data associated with the package. In all other respects they are equivalent to the matching functions.

Tcl_PkgRequireProc is the form of package require handling multiple requirements. The other forms are present for backward compatibility and translate their invocations to this form.

### KEYWORDS

package, present, provide, require, version

### SEE ALSO

package, Tcl_StaticPackage
Copyright © 1996 Sun Microsystems, Inc.