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我试图在 Swift 中解决 Project Euler 的第 25 个(https://projecteuler.net/problem=25)问题，当我在 while 循环中更改条件时收到了一条非常神秘的错误消息。
起初，我从 2 开始，然后是 10，并得到了正确的结果。但是当输入 100 时，程序崩溃了。
var index = 3
var a = 1
var b = 2
while String(b).characters.count < 100 {
let temp = b
b = a + b
a = temp
index += 1
}
print(index)
这是错误:
0 swift 0x00000001103b24f7 PrintStackTraceSignalHandler(void*) + 39
1 swift 0x00000001103b19a6 SignalHandler(int) + 646
2 libsystem_platform.dylib 0x00007fffb3a89b3a _sigtramp + 26
3 libswiftCore.dylib 0x0000000112d6a40d (anonymous namespace)::Sentinels + 12861
4 swift 0x000000010dcfadcf llvm::MCJIT::runFunction(llvm::Function*, llvm::ArrayRef<llvm::GenericValue>) + 655
5 swift 0x000000010dd009c3 llvm::ExecutionEngine::runFunctionAsMain(llvm::Function*, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, char const* const*) + 707
6 swift 0x000000010d1fdc69 swift::RunImmediately(swift::CompilerInstance&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, swift::IRGenOptions&, swift::SILOptions const&) + 3385
7 swift 0x000000010d1d2622 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 50738
8 swift 0x000000010d17fd6c main + 9052
9 libdyld.dylib 0x00007fffb387a235 start + 1
Stack dump:
0. Program arguments: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -interpret ./project-euler/025/problem025.swift -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -color-diagnostics -module-name problem025
[1] 8705 illegal hardware instruction ./project-euler/025/problem025.swift
有人知道为什么会这样吗？完全相同的代码在 Python 和 Ruby 中运行流畅。