objective-c Objective C Unicode 字符比较
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Objective C unicode character comparisons
提问by Alan
How are unicode comparisons coded? I need to test exactly as below, checking for specific letters in a string. The code below chokes: warning: comparison between pointer and integer
unicode 比较是如何编码的？我需要完全按照下面的方式进行测试，检查字符串中的特定字母。下面的代码窒息：警告：指针和整数之间的比较
for (charIndex = 0; charIndex < [myString length]; charIndex++)
{
unichar testChar = [myString characterAtIndex:charIndex];
if (testChar == "A")
// do something
if (testChar == "B")
// do something
if (testChar == "C")
// do something
}
回答by Jarret Hardie
For char literals, use single quotes:
对于字符文字，使用单引号：
if (testChar == 'A') NSLog(@"It's an A");
Or represent the character using the code point number:
或使用代码点编号表示字符：
if (testChar == 0x1e01) NSLog(@"It's an A with a ring below");
The compiler sees double-quotes as a string, so builds "A" as equivalent to a const char *(which gives you there error message about the pointer).
编译器将双引号视为字符串，因此将“A”构建为等效于 a const char *（它会为您提供有关指针的错误消息）。
回答by harveyswik
What are you really trying to do? Doing direct character comparisons is unusual. Typically -compare: or -isEqual: would be used to compare two strings. Or NSScanner would be used to analyze the components of a string.
你真正想要做什么？进行直接的字符比较是不寻常的。通常 -compare: 或 -isEqual: 将用于比较两个字符串。或者 NSScanner 将用于分析字符串的组成部分。
