C++ - 使用 >> 运算符读取文件直到到达行尾
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C++ - Read file until reaching end of line with >> operators
提问by pineapple-na
I have looked around a lot, and still not found how to do this, so, please bear with me.
我已经环顾了很多，仍然没有找到如何做到这一点，所以，请耐心等待。
Let's say i have to read a txt file that contains different kinds of data, where the first float is an id, and then there are a few (not always the same amount) of other floats representing other stuff... times, for example, in pairs.
假设我必须读取一个包含不同类型数据的 txt 文件，其中第一个浮点数是一个 id，然后有一些（并不总是相同数量）其他浮点数代表其他东西......时间，例如， 成对。
So the file would look something like:
所以文件看起来像：
1 0.2 0.3
2.01 3.4 5.6 5.7
3 2.0 4.7
...
After a lot of research, I ended up with a function like this:
经过大量研究，我最终得到了这样的函数：
vector<Thing> loadThings(char* filename){
vector<Thing> things;
ifstream file(filename);
if (file.is_open()){
while (true){
float h;
file >> h; // i need to load the first item in the row for every thing
while ( file.peek() != '\n'){
Thing p;
p.id = h;
float f1, f2;
file >> f1 >> f2;
p.ti = f1;
p.tf = f2;
things.push_back(p);
if (file.eof()) break;
}
if (file.eof()) break;
}
file.close();
}
return things;
}
but the while loop with the (file.peek() != '\n')condition never finishes by itself, i mean... peek never equals '\n'
但是带有(file.peek() != '\n')条件的 while 循环永远不会自行完成，我的意思是... peek never equals'\n'
does anybody have an idea why? Or perhaps some other way to read the file using >>operators?!
Thank you very much!
有谁知道为什么？或者也许是使用>>运算符读取文件的其他方法？！非常感谢！
回答by user1538798
just suggesting another way, why not use
只是建议另一种方式，为什么不使用
// assuming your file is open
string line;
while(!file.eof())
{
getline(file,line);
// then do what you need to do
}
回答by SHR
To skip any character you should try to call a function like this before reaching the while(file.peek() != '\n')
要跳过任何字符，您应该尝试在到达之前调用这样的函数 while(file.peek() != '\n')
istream& eatwhites(istream& stream)
{
const string ignore=" \t\r"; //list of character to skip
while(ignore.find(stream.peek())){
stream.ignore();
}
return stream;
}
A better solution is to read the whole line into string than use istringstreamto parse it.
更好的解决方案是将整行读入字符串而不是用于istringstream解析它。
float f;
string line;
std::getline(file, line);
istringstream fin(line)
while(fin>>f){ //loop till end of line
}
回答by pineapple-na
With a little help from you and other friends i ended up changeing the code to use getline() instead. Here is the result, hope it helps someone.
在您和其他朋友的帮助下，我最终将代码更改为使用 getline()。这是结果，希望它可以帮助某人。
typedef struct Thing{
float id;
float ti;
float tf;
};
vector<Thing> loadThings(char* filename){
vector<Thing> things;
ifstream file(filename);
if (file.is_open()){
string line;
while(getline(file, line))
{
istringstream iss(line);
float h;
iss >> h;
float f1, f2;
while (iss >> f1 >> f2)
{
Thing p;
p.id = h;
p.ti = f1;
p.tf = f2;
things.push_back(p);
}
}
file.close();
}
return things;
}
Thank you for your time!
感谢您的时间！
