## Tcl8.6.0/Tk8.6.0 Documentation > Tcl C API, version 8.6.0 > GetVersion

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### NAME

Tcl_GetVersion — get the version of the library at runtime

### SYNOPSIS

#include <tcl.h>
Tcl_GetVersion(major, minor, patchLevel, type)

### ARGUMENTS

int *major (out)
  Major version number of the Tcl library.

int *minor (out)
  Minor version number of the Tcl library.

int *patchLevel (out)
  The patch level of the Tcl library (or alpha or beta number).

Tcl_ReleaseType *type (out)
  The type of release, also indicates the type of patch level. Can be one of TCL_ALPHA_RELEASE, TCL_BETA_RELEASE, or TCL_FINAL_RELEASE.

### DESCRIPTION

Tcl_GetVersion should be used to query the version number of the Tcl library at runtime. This is useful when using a dynamically loaded Tcl library or when writing a stubs-aware extension. For instance, if you write an extension that is linked against the Tcl stubs library, it could be loaded into a program linked to an older version of Tcl than you expected. Use Tcl_GetVersion to verify that fact, and possibly to change the behavior of your extension.

Tcl_GetVersion accepts NULL for any of the arguments. For instance if you do not care about the patchLevel of the library, pass a NULL for the patchLevel argument.

### KEYWORDS

version, patchlevel, major, minor, alpha, beta, release
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