This class represents a CRC‐32 checksum value that can be updated as data is provided.

Synopsis

Declared in <bdlde_crc32.h>

class Crc32;

Description

More generally, this class supports a complete set of value semantic operations, including copy construction, assignment, equality comparison, ostream printing, and bdex serialization. (A precise operational definition of when two objects have the same value can be found in the description of operator== for the class.) This class is *exception neutral* with no guarantee of rollback: if an exception is thrown during the invocation of a method on a pre‐existing object, the class is left in a valid state, but its value is undefined. In no event is memory leaked. Finally, aliasing (e.g., using all or part of an object as both source and destination) is supported in all cases.

Member Functions

Name

Description

Crc32 [constructor]

Constructors

operator=

Assign to this checksum the value of the specified rhs checksum, and return a reference to this modifiable checksum.

bdexStreamIn

Assign to this object the value read from the specified input stream using the specified version format, and return a reference to stream. If stream is initially invalid, this operation has no effect. If version is not supported, this object is unaltered and stream is invalidated but otherwise unmodified. If version is supported but stream becomes invalid during this operation, this object has an undefined, but valid, state. Note that no version is read from stream. See the bslx package‐level documentation for more information on BDEX streaming of value‐semantic types and containers.

bdexStreamOut

Write this value to the specified output stream using the specified version format, and return a reference to stream. If stream is initially invalid, this operation has no effect. If version is not supported, stream is invalidated but otherwise unmodified. Note that version is not written to stream. See the bslx package‐level documentation for more information on BDEX streaming of value‐semantic types and containers.

checksum

Return the current value of this checksum.

checksumAndReset

Return the current value of this checksum and set the value of this checksum to the value the default constructor provides.

print

Format this object to the specified output stream at the (absolute value of) the optionally specified indentation level and return a reference to stream. If level is specified, optionally specify spacesPerLevel, the number of spaces per indentation level for this and all of its nested objects. If level is negative, suppress indentation of the first line. If spacesPerLevel is negative, format the entire output on one line, suppressing all but the initial indentation (as governed by level). If stream is not valid on entry, this operation has no effect.

reset

Reset the value of this checksum to the value the default constructor provides.

update

Update the value of this checksum to incorporate the specified data having the specified length. If the current state is the default state, the resultant value of this checksum is the application of the CRC‐32 algorithm upon the currently given data of the given length. If this checksum has been previously provided data and has not been subsequently reset, the current state is not the default state and the resultant value is equivalent to applying the CRC‐32 algorithm upon the concatenation of all the provided data. Note that if data is 0, then length also must be 0.

view

Return the current value of this checksum.

Static Member Functions

Name

Description

maxSupportedBdexVersion

maxSupportedBdexVersion overloads

Friends

Name

Description

BloombergLP::bdlde::operator==

Return true if the specified lhs and rhs checksums have the same value, and false otherwise. Two checksums have the same value if the values obtained from their checksum methods are identical.

Non-Member Functions

Name

Description

operator!=

Return true if the specified lhs and rhs checksums do not have the same value, and false otherwise. Two checksums do not have the same value if the values obtained from their checksum methods differ.

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