使用逗号作为分隔符的 C++ getline 多个变量类型
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C++ getline multiple variable types using comma as delimiter
提问by user2661167
I'm trying to do a home work assignment which requires data fro a txt file to be read in to variables. The file has this on each line "surname, initials, number, number". I have got the get line working partially using the following code.
我正在尝试做一个家庭作业，它需要将 txt 文件中的数据读入变量。该文件的每一行都有这个“姓氏，姓名首字母，数字，数字”。我已经使用以下代码使 get 线部分工作。
ifstream inputFile("Students.txt");
string line;
string Surname;
string Initial;
int number1, number2;
while (getline(inputFile, line))
{
stringstream linestream(line);
getline(linestream, Surname, ',');
getline(linestream, Initial, ',');
getline(linestream, number1, ',');
getline(linestream, number2, ',');
cout << Surname << "---" << Initial << "-" << number1 << "-" << number2 << endl;
}
This throws a compile error, but if I declare number1 and number2 as strings it works fine. So my question is, do I have to getline as a string then convert to an int variable or is there a better way?
这会引发编译错误，但如果我将 number1 和 number2 声明为字符串，它就可以正常工作。所以我的问题是，我是否必须将 getline 作为字符串然后转换为 int 变量还是有更好的方法？
回答by Oli_G
Yes, the second parameter of getline function must be a string by definition and it will contain your extracted string. Simply declare number1 and number2 as string and then convert them to Integer with stoi() (C++11) or atoi() function :
是的，getline 函数的第二个参数必须是定义的字符串，它将包含您提取的字符串。只需将 number1 和 number2 声明为字符串，然后使用 stoi() (C++11) 或 atoi() 函数将它们转换为整数：
string strNumber1;
string strNumber2;
getline(linestream, strNumber1, ',');
getline(linestream, strNumber2, ',');
int number1 = stoi(strNumber1);
int number2 = atoi(strNumber2.c_str());
Hope this helps
希望这可以帮助
回答by 0x499602D2
std::getlinetakes as a first parameter an object of std::basic_istream. It won't work for any other object.
std::getline将 的对象作为第一个参数std::basic_istream。它不适用于任何其他对象。
What I did was use the csv_whitespaceclass to add a comma as a delimeter. For example:
我所做的是使用csv_whitespace该类添加逗号作为分隔符。例如：
class csv_whitespace
: public std::ctype<char>
{
public:
static const mask* make_table()
{
static std::vector<mask> v(classic_table(), classic_table() + table_size);
v[','] |= space;
v[' '] |= space;
return &v[0];
}
csv_whitespace(std::size_t refs = 0) : ctype(make_table(), false, refs) { }
};
int main()
{
std::ifstream in("Students.txt");
std::string line;
std::string surname;
std::string initial;
int number1, number2;
while (std::getline(in, line))
{
std::stringstream linestream(line);
linestream.imbue(std::locale(linestream.getloc(), new csv_whitespace));
getline(linestream, surname, ',');
getline(linestream, initial, ',');
linestream >> number1 >> number2;
}
}
