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534. Missing basic_string members

Section: 27.4.3[basic.string]Status:CD1Submitter: Alisdair MeredithOpened: 2005-11-16Last modified: 2016-01-28

Priority:Not Prioritized

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Discussion:

OK, we all know std::basic_string is bloated and already has way toomany members. However, I propose it is missing 3 useful members thatare often expected by users believing it is a close approximation of thecontainer concept. All 3 are listed in table 71 as 'optional'

i/ pop_back.

This is the one I feel most strongly about, as I only just discovered itwas missing as we are switching to a more conforming standard library<g>

I find it particularly inconsistent to support push_back, but notpop_back.

ii/ back.

There are certainly cases where I want to examine the last character ofa string before deciding to append, or to trim trailing path separatorsfrom directory names etc. *rbegin() somehow feels inelegant.

iii/ front

This one I don't feel strongly about, but if I can get the first two,this one feels that it should be added as a 'me too' for consistency.

I believe this would be similarly useful to the data() member recentlyadded to vector, or at() member added to the maps.

Proposed resolution:

Add the following members to definition of class template basic_string, 21.3p7

void pop_back ()const charT & front() constcharT & front()const charT & back() constcharT & back()

Add the following paragraphs to basic_string description

21.3.4p5

const charT & front() constcharT & front()

Precondition:!empty()

Effects: Equivalent tooperator[](0).

21.3.4p6

const charT & back() constcharT & back()

Precondition:!empty()

Effects: Equivalent tooperator[]( size() - 1).

21.3.5.5p10

void pop_back ()

Precondition:!empty()

Effects: Equivalent toerase( size() - 1, 1 ).

Update Table 71: (optional sequence operations)Add basic_string to the list of containers for the following operations.

a.front()a.back()a.push_back()a.pop_back()a[n]

[Berlin: Has support. Alisdair provided wording.]