使用C++的RWCString读取文本文件时触发RWBoundsErr错误的原因咨询

Hey there! Let's break down exactly why that RWBoundsErr is popping up when you use RWCString to read your text files (and why your commented-out code works fine).

First, let's get the basics straight: RWBoundsErr is Rogue Wave's specific exception for out-of-bounds access—meaning you're trying to access a position in your RWCString that doesn't exist (like an index that's negative, or larger than the string's actual length).

Now, tying this to your scenario (files with trailing spaces on every line), here are the most likely culprits:

• Unchecked index handling for trailing spaces
  Chances are your error-throwing code is manually stripping trailing spaces by iterating backward from the end of the string. For example:

  // Example of risky code that could trigger the error
  size_t idx = currentLine_.length() - 1;
  while (currentLine_[idx] == ' ') {
      idx--;
  }
  currentLine_.erase(idx + 1);
  

  If a line is all spaces (or becomes empty after trimming), idx will keep decrementing past 0 until it's negative. When you try to access currentLine_[idx] with a negative index, RWCString's boundary checks kick in and throw RWBoundsErr. Your commented-out code probably uses a safer method like RWCString::rtrim()—a built-in function that handles edge cases like all-space lines internally without crossing boundaries.

• Missing length checks before accessing characters
  If your code directly accesses characters (e.g., currentLine_[0]) without first checking if currentLine_ is empty, you'll hit this error when reading an empty line. The commented-out code likely adds a guard clause (like if (!currentLine_.isEmpty())) before accessing specific positions, avoiding the invalid access.

• Flawed line-reading logic
  If your line-reading code doesn't properly handle empty lines or the end of the file, it might leave currentLine_ in an invalid state (e.g., a zero-length string that your code still tries to manipulate). The working code probably uses a more robust line-reading approach (like leveraging RWCString's built-in line-reading methods or pairing std::getline with RWCString's constructor) that correctly initializes the string even for empty lines.

At the core of it all: your error-throwing code lacks proper boundary checks for edge cases (all-space lines, empty lines) that come up with your file format. The working code either uses library functions that handle these cases safely or adds explicit checks to avoid invalid index access.

内容的提问来源于stack exchange，提问作者Anish Kumar