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[SR-2131] The empty string is not a prefix/suffix of itself (or any string) #44739

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swift-ci opened this issue Jul 21, 2016 · 1 comment
Closed

[SR-2131] The empty string is not a prefix/suffix of itself (or any string) #44739

swift-ci opened this issue Jul 21, 2016 · 1 comment
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. feature A feature request or implementation standard library Area: Standard library umbrella

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@swift-ci
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Previous ID SR-2131
Radar None
Original Reporter abl (JIRA User)
Type Bug
Status Resolved
Resolution Done
Additional Detail from JIRA
Votes 0
Component/s Standard Library
Labels Bug, LanguageFeatureRequest
Assignee abl (JIRA)
Priority Medium

md5: d4b6fd317e1bd24e83fe8dec7117f5da

Issue Description:

Inspired by https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160718/024896.html.

Currently, the empty string has unique prefix/suffix behavior compared to other strings:

let E = ""
let a = "a"  // any non-empty string
let b = "b"  // any non-empty string

a == a  // true
a.hasPrefix(a)  // true
a.hasSuffix(a)  // true
(a+b).hasSuffix(b)  // true
(b+a).hasPrefix(b)  // true

E == E  // true
E.hasPrefix(E)  // false
E.hasSuffix(E)  // false
(a+E).hasSuffix(E)  // false
(E+a).hasPrefix(E)  // false

This is consistent with NSString and Foundation but conflicts with other languages and with concatenation - for all non-empty strings a and b, (a+b) has a prefix of a and a suffix of b.
@swift-ci
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Comment by Alexander Lash (JIRA)

Resolved in #3651

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
This issue was closed.
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. feature A feature request or implementation standard library Area: Standard library umbrella
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