我如何从字符串变量使用Swift删除最后一个字符?在文档中找不到。
下面是完整的例子:
var expression = "45+22"
expression = expression.substringToIndex(countElements(expression) - 1)
我如何从字符串变量使用Swift删除最后一个字符?在文档中找不到。
下面是完整的例子:
var expression = "45+22"
expression = expression.substringToIndex(countElements(expression) - 1)
当前回答
全局的dropLast()函数作用于序列,因此也作用于字符串:
var expression = "45+22"
expression = dropLast(expression) // "45+2"
// in Swift 2.0 (according to cromanelli's comment below)
expression = String(expression.characters.dropLast())
其他回答
var str = "Hello, playground"
extension String {
var stringByDeletingLastCharacter: String {
return dropLast(self)
}
}
println(str.stringByDeletingLastCharacter) // "Hello, playgroun"
Swift 3:当你想删除尾随字符串:
func replaceSuffix(_ suffix: String, replacement: String) -> String {
if hasSuffix(suffix) {
let sufsize = suffix.count < count ? -suffix.count : 0
let toIndex = index(endIndex, offsetBy: sufsize)
return substring(to: toIndex) + replacement
}
else
{
return self
}
}
修剪字符串最后一个字符最简单的方法是:
title = title[title.startIndex ..< title.endIndex.advancedBy(-1)]
一个快速变化的类别:
extension String {
mutating func removeCharsFromEnd(removeCount:Int)
{
let stringLength = count(self)
let substringIndex = max(0, stringLength - removeCount)
self = self.substringToIndex(advance(self.startIndex, substringIndex))
}
}
使用:
var myString = "abcd"
myString.removeCharsFromEnd(2)
println(myString) // "ab"
我更喜欢下面的实现,因为我不必担心,即使字符串是空的
let str = "abc"
str.popLast()
// Prints ab
str = ""
str.popLast() // It returns the Character? which is an optional
// Print <emptystring>