[#bsl-basic_string-02]
= xref:bsl.adoc[bsl]::xref:bsl/basic_string-0faf.adoc[basic_string<CHAR_TYPE>]
:relfileprefix: ../
:mrdocs:

Deduce the template parameter `CHAR_TYPE` from the `value_type` of the iterators passed to passed to the constructor of `basic_string`. This deduction guide does not participate unless the specified `ALLOC` is convertible to `bsl::allocator<CHAR_TYPE>`.

== Synopsis

Declared in `<bslstl_string.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class INPUT_ITER,
    class CHAR_TYPE = xref:BloombergLP/bslstl/IteratorUtil/IterVal_t.adoc[BloombergLP::bslstl::IteratorUtil::IterVal_t<INPUT_ITER>],
    class ALLOC,
    class DEFAULT_ALLOCATOR = xref:bsl/allocator-0df.adoc[bsl::allocator<CHAR_TYPE>]>
requires bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>
xref:bsl/basic_string-0faf.adoc[basic_string<CHAR_TYPE>](
    INPUT_ITER,
    INPUT_ITER,
    ALLOC*) -> xref:bsl/basic_string-0faf.adoc[basic_string<CHAR_TYPE>];
----


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