5 
#include <iostream>
#include <string>
#include <vector>

/*
  Using STL's string class because the problem does not refer any
  limits regarding the number of characters per line.
 */

using namespace std;

int main()
{
  string line;
  vector<string> lines;
  while (getline(cin, line))
  {
    lines.push_back(line);
  }

  unsigned int i, u;
  unsigned int opening = 1; // 2 if last was opening, 1 if it was closing
  for (i = 0; i < (int) lines.size(); i++)
  {
    for (u = 0; u < (int) lines[u].length(); u++)
    {

    }
  }

  return 0;
}

我有一个简单的代码，它只读取几行（输入文件）：

"To be or not to be," quoth the Bard, "that
is the question".
The programming contestant replied: "I must disagree.
To `C' or not to `C', that is The Question!"

但是，我发现它是 SEGFAULTing，因为它在第一行（第 4 个字符）读取了一个 ' ' （空格）字符：

(gdb) run < texquotes_input.txt 
Starting program: /home/david/src/oni/texquotes < texquotes_input.txt

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7b92533 in std::string::length() const () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6

我真的不明白为什么，我没有在循环内做任何事情，我只是在循环。

4

2 回答 2

6

我已经发现了问题。这是内循环：

for (u = 0; u < (int) lines[u].length(); u++)
{

}

应该：

for (u = 0; u < (int) lines[i].length(); u++)
{

}
于 2013-03-03T15:15:27.920 回答
2

在另一个答案中，索引错字已经被发现。

我想补充一点，使用基于范围的for循环这些问题更难发生，因为循环有点“隐含”：

#include <iostream>
#include <string>
#include <vector>
using namespace std;

int main()
{
  string line;
  vector<string> lines;
  while (getline(cin, line))
  {
    lines.push_back(line);
  }

  for ( const auto& currLine : lines )
  {
    for ( auto ch : currLine )
    {
      cout << ch;  
    }
    cout << '\n';
  }
}
于 2013-03-03T15:51:29.187 回答