我正在尝试编写一个排序程序，试图对我拥有的数据集进行排序。排序的关键是 Grid_ID，它恰好是一个字母数字数据。我试图相应地排序
它给了我一个错误
在抛出 'std::out_of_range' 的实例后调用终止
what(): basic_string::at: __n (which is 0) >= this->size() (which is 0)
在进行调试时，代码的读取部分似乎可以正常工作。将文件内容读取到 DataContainer 数据中会填充正确的键和文本位置数据。但是当涉及到 std::sort 时，当调用程序“less”时，const GridLabel& elem2 在第二次迭代后总是为零或 null
下面是一些数据集和部分源代码（我这里不包括按排序顺序写的内容，但应该是可运行的）
感谢帮助！
这是部分数据集
Grid_Id,Speed,Acc,ID
K31,173,8.37,1
K29,143,3.36,2
K29,107,4.56,3
K30,133,5.97,4
K30,153,2.38,5
J27,203,1.86,6
J27,143,1.59,7
I26,73,7.66,8
I27,134,2.86,9
这是代码
#include
#include
#include
#include
#include
#include
#include
#include
struct GridLabel
{
std::string key_;
std::istream::pos_type pos_; // position in stream where this line starts
GridLabel( const std::string& key, const std::istream::pos_type& pos) : key_( key)
, pos_( pos)
{
}
const GridLabel& operator=( const GridLabel& other)
{
key_ = other.key_;
pos_ = other.pos_;
return *this;
}
};
typedef std::vector< GridLabel> DataContainer;
// Return whether first element is smaller than the second
bool less( const GridLabel& elem1, const GridLabel& elem2 )
{
std::stringstream ss1, ss2;
ss1 << elem1.key_.at(0);
ss2 << elem2.key_.at(0);
int value = (ss1.str()).compare(ss2.str());
if( value < 0 )
{
return true;
}
else if( value == 0)
{
// need to check if the rest are smaller
std::string substr1 = elem1.key_.substr(1, std::string::npos);
std::string substr2 = elem2.key_.substr(1, std::string::npos);
return (std::atoi(substr1.c_str()) < std::atoi(substr2.c_str()));
}
else
{
return false;
}
}
int main(int argc, char* argv[])
{
DataContainer data;
// read data into the vector here
std::ifstream input( "some_file.csv");
// check if it is correct
if ( !input.good())
{
std::cerr << "Input file can not be openned." << std::endl;
return -1;
}
std::string text;
std::string key;
std::istream::pos_type pos;
int count=0, save=0;
// to skip the header
std::getline( input, text);
for( int line = 0; !input.eof(); ++line)
{
// store the position before reading the line
pos = input.tellg();
std::getline( input, text);
// parse it
save = text.find(",");
key = text.substr(0,(save));
data.push_back( GridLabel( key, pos));
}
// sort the data in sorted order
std::sort( data.begin(), data.end(), less);
// create the new file
...............
return 0;
}