A seed sequence is an object that consumes a sequence of integer-valued data and produces a requested number of unsigned integer values i, 0≤i<232, based on the consumed data. [ Note: Such an object provides a mechanism to avoid replication of streams of random variates. This can be useful, for example, in applications requiring large numbers of random number engines. — end note ]
A class S satisfies the requirements of a seed sequence if the expressions shown in Table 102 are valid and have the indicated semantics, and if S also satisfies all other requirements of this section [rand.req.seedseq]. In that Table and throughout this section:
a)T is the type named by S's associated result_type;
b)q is a value of S and r is a possibly const value of S;
c)ib and ie are input iterators with an unsigned integer value_type of at least 32 bits;
d)rb and re are mutable random access iterators with an unsigned integer value_type of at least 32 bits;
e)ob is an output iterator; and
f)il is a value of initializer_list<T>.
| Expression | Return type | Pre/post-condition | Complexity |
| S::result_type | T | T is an unsigned integer type of at least 32 bits. | compile-time |
| S() | Creates a seed sequence with the same initial state as all other default-constructed seed sequences of type S. | constant | |
| S(ib,ie) | Creates a seed sequence having internal state that depends on some or all of the bits of the supplied sequence [ib,ie). | O(ie−ib) | |
| S(il) | Same as S(il.begin(), il.end()). | same as S(il.begin(), il.end()) | |
| q.generate(rb,re) | void | Does nothing if rb == re. Otherwise, fills the supplied sequence [rb,re) with 32-bit quantities that depend on the sequence supplied to the constructor and possibly also depend on the history of generate's previous invocations. | O(re−rb) |
| r.size() | size_t | The number of 32-bit units that would be copied by a call to r.param. | constant |
| r.param(ob) | void | Copies to the given destination a sequence of 32-bit units that can be provided to the constructor of a second object of type S, and that would reproduce in that second object a state indistinguishable from the state of the first object. | O(r.size()) |