string.compare()方法使用疑问：能否用于跨文化场景下的字符串比较？

First, let’s clear up a small misunderstanding in your description: the return value of string.compare() isn’t only determined by string length. Instead, it does a character-by-character lexicographical comparison (using ASCII values when we ignore cultural differences):

• Returns 0 if the two strings are identical (content and length match exactly)
• Returns a negative value if the first string comes before the second in lex order—this can happen either because a differing character has a smaller ASCII value, or all matching characters are the same and the first string is shorter
• Returns a positive value if the first string comes after the second in lex order—either because a differing character has a larger ASCII value, or all matching characters are identical and the first string is longer

Now, to answer your question: whether string.compare() is suitable depends entirely on what you’re trying to accomplish:

When it’s a great fit #

• Lexicographical sorting or ordering: If you need to sort a list of strings, or figure out if one string comes before/after another in dictionary order, compare() is perfect. It’s efficient (stops at the first differing character) and built specifically for this use case. For example:

  // C++ example
  std::string a = "apple", b = "banana";
  if (a.compare(b) < 0) {
      // "apple" comes before "banana" in lex order
  }
  

• Checking exact equality (though not the most readable choice): Since compare() == 0 means the strings are identical, this works—but using language-specific equality checks (like == in C++, String.equals() in Java) is more intuitive, as it makes your intent immediately clear to other developers.

When it’s not suitable #

• Checking if one string contains another: compare() tells you nothing about substring relationships. To check if string A is a substring of string B, use dedicated methods (like string.find() in C++, String.contains() in Java).
• Comparing string lengths directly: If you only care which string is longer, use the length property (e.g., a.length() > b.length()) instead. compare()’s positive/negative return doesn’t reliably indicate length differences—for example, "z" vs "aa" returns a positive value even though "z" is shorter.
• Checking partial matches: While some implementations let you compare specific parts of strings via compare() overloads, if you’re not careful with these parameters, you might get unexpected results. For partial matches, it’s often clearer to extract the substrings first and then compare.

Final Verdict #

If your goal is lexicographical comparison or exact equality checks (and you don’t mind slightly less readability for equality), string.compare() is fully suitable when ignoring cultural differences. For any other use case—like substring checks or direct length comparisons—stick to methods designed specifically for those tasks.

内容的提问来源于stack exchange，提问作者karunakar bhogyari