# Glib::Checksum Class Reference

Computes the checksum for data. More...

`#include <glibmm/checksum.h>`

List of all members.

## Public Types

enum | ChecksumType { CHECKSUM_MD5, CHECKSUM_SHA1, CHECKSUM_SHA256 }

## Public Member Functions

| Checksum ()
| Checksum (GChecksum* castitem, bool make_a_copy=false)
| Checksum (const Checksum& src)
Checksum& | operator= (const Checksum& src)
| ~Checksum ()
GChecksum* | gobj ()
const GChecksum* | gobj () const
GChecksum* | gobj_copy () const
| Provides access to the underlying C instance. The caller is responsible for freeing it. Use when directly setting fields in structs.
| Checksum (ChecksumType checksum_type)
| Creates a new Checksum, using the checksum algorithm checksum_type.
| operator bool () const
| Returns true if the Checksum object is valid.
void | reset ()
| Resets the state of the checksum back to its initial state.
void | update (const guchar* data, gsize length)
| Feeds data into an existing Checksum.
void | update (const std::string& data)
| Feeds data into an existing Checksum.
void | get_digest (guint8* buffer, gsize* digest_len) const
| Gets the digest from checksum as a raw binary vector and places it into buffer.
std::string | get_string () const
| Gets the digest as an hexadecimal string.

## Static Public Member Functions

static std::string | compute_checksum (ChecksumType type, const guchar* data, gsize length)
| Computes the checksum for a binary data of length.
static std::string | compute_checksum (ChecksumType type, const std::string& str)
| Computes the checksum of a string.
static gssize | get_length (ChecksumType checksum_type)
| Gets the length in bytes of digests of type checksum_type.

## Protected Attributes

GChecksum* | gobject_

## Related Functions

(Note that these are not member functions.)
Glib::Checksum | wrap (GChecksum* object, bool take_copy=false)
| A Glib::wrap() method for this object.

## Detailed Description

Computes the checksum for data.

This is a generic API for computing checksums (or "digests") for a sequence of arbitrary bytes, using various hashing algorithms like MD5, SHA-1 and SHA-256. Checksums are commonly used in various environments and specifications.

glibmm supports incremental checksums by calling update() as long as there's data available and then using get_string() or get_digest() to compute the checksum and return it either as a string in hexadecimal form, or as a raw sequence of bytes. To compute the checksum for binary blobs and NULL-terminated strings in one go, use the static compute_checksum() convenience functions().

Since glibmm 2.16:

## Member Enumeration Documentation

enum Glib::Checksum::ChecksumType

Enumerator:

  CHECKSUM_MD5 |
  CHECKSUM_SHA1 |
  CHECKSUM_SHA256 |

## Constructor & Destructor Documentation

Glib::Checksum::Checksum | ( |  | ) |

Glib::Checksum::Checksum | ( | GChecksum * | castitem,
|  | bool | make_a_copy = `false` |
| ) |  |  | `[explicit]`

Glib::Checksum::Checksum | ( | const Checksum& | src | ) |

Glib::Checksum::~Checksum | ( |  | ) |

Glib::Checksum::Checksum | ( | ChecksumType | checksum_type | ) | `[explicit]`

Creates a new Checksum, using the checksum algorithm checksum_type.

If the checksum_type is not known, then operator bool() will return false.

Parameters:

  | type | checksum type, one of defined above.

## Member Function Documentation

static std::string Glib::Checksum::compute_checksum | ( | ChecksumType | type,
|  | const std::string & | str |
| ) |  |  | `[static]`

Computes the checksum of a string.

Parameters:

  | checksum_type | A ChecksumType
  | str | The string to compute the checksum of.

Returns:
  The checksum as a hexadecimal string.

static std::string Glib::Checksum::compute_checksum | ( | ChecksumType | type,
|  | const guchar * | data,
|  | gsize | length |
| ) |  |  | `[static]`

Computes the checksum for a binary data of length.

This is a convenience wrapper for g_checksum_new(), g_checksum_get_string() and g_checksum_free().

The hexadecimal string returned will be in lower case.

Since glibmm 2.16:

Parameters:

  | checksum_type | A ChecksumType.
  | data | Binary blob to compute the digest of.
  | length | Length of data.

Returns:
  The digest of the binary data as a string in hexadecimal. The returned string should be freed with g_free() when done using it.

void Glib::Checksum::get_digest | ( | guint8 * | buffer,
|  | gsize * | digest_len |
| ) |  |  | const

Gets the digest from checksum as a raw binary vector and places it into buffer.

The size of the digest depends on the type of checksum.

Once this function has been called, the Checksum is closed and can no longer be updated with g_checksum_update().

Since glibmm 2.16:

Parameters:

  | buffer | Output buffer.
  | digest_len | An inout parameter. The caller initializes it to the size of buffer. After the call it contains the length of the digest.

static gssize Glib::Checksum::get_length | ( | ChecksumType | checksum_type | ) | `[static]`

Gets the length in bytes of digests of type checksum_type.

Parameters:

  | checksum_type | A ChecksumType.

Returns:
  The checksum length, or -1 if checksum_type is not supported.

std::string Glib::Checksum::get_string | ( |  | ) | const

Gets the digest as an hexadecimal string.

Once this function has been called the Checksum can no longer be updated with g_checksum_update().

The hexadecimal characters will be lower case.

Since glibmm 2.16:

Returns:
  The hexadecimal representation of the checksum. The returned string is owned by the checksum and should not be modified or freed.

const GChecksum* Glib::Checksum::gobj | ( |  | ) | const`[inline]`

GChecksum* Glib::Checksum::gobj | ( |  | ) | `[inline]`

GChecksum* Glib::Checksum::gobj_copy | ( |  | ) | const

Provides access to the underlying C instance. The caller is responsible for freeing it. Use when directly setting fields in structs.

Glib::Checksum::operator bool | ( |  | ) | const

Returns true if the Checksum object is valid.

This will return false, for instance, if an unsupported checksum type was provided to the constructor.

Checksum& Glib::Checksum::operator= | ( | const Checksum& | src | ) |

void Glib::Checksum::reset | ( |  | ) |

Resets the state of the checksum back to its initial state.

Since glibmm 2.18:

void Glib::Checksum::update | ( | const std::string & | data | ) |

Feeds data into an existing Checksum.

The checksum must still be open, that is get_string() or get_digest() must not have been called on the checksum.

Parameters:

  | data | Buffer used to compute the checksum

void Glib::Checksum::update | ( | const guchar * | data,
|  | gsize | length |
| ) |  |  |

Feeds data into an existing Checksum.

The checksum must still be open, that is g_checksum_get_string() or g_checksum_get_digest() must not have been called on checksum.

Since glibmm 2.16:

Parameters:

  | data | Buffer used to compute the checksum.
  | length | Size of the buffer, or -1 if it is a null-terminated string.

## Friends And Related Function Documentation

Glib::Checksum wrap | ( | GChecksum * | object,
|  | bool | take_copy = `false` |
| ) |  |  | `[related]`

A Glib::wrap() method for this object.

Parameters:

  | object | The C instance.
  | take_copy | False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns:
  A C++ instance that wraps this C instance.

## Member Data Documentation

GChecksum* Glib::Checksum::gobject_`[protected]`