从 C++ 中的文件读取直到行尾？
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Read from file in c++ till end of line?
提问by user3050163
How can i read data untill end of line?I have a text file "file.txt" with this
如何读取数据直到行尾？我有一个文本文件“file.txt”
1 5 9 2 59 4 6
2 1 2
3 2 30 1 55
I have this code:
我有这个代码：
ifstream file("file.txt",ios::in);
while(!file.eof())
{
....//my functions(1)
while(?????)//Here i want to write :while (!end of file)
{
...//my functions(2)
}
}
in my functions(2) i use the data from the lines and it need to be Int ,not char
在我的函数（2）中，我使用行中的数据，它需要是 Int ，而不是 char
回答by herohuyongtao
Don't use while(!file.eof())as eof()will only be set after reading the end of the file. It does not indicate, that the next read will be the end of the file. You can use while(getline(...))instead and combine with istringstreamto read numbers.
不要使用while(!file.eof())aseof()只会在读取文件末尾后设置。它并不表示下一次读取将是文件的结尾。您可以while(getline(...))改用并结合使用istringstream来读取数字。
#include <fstream>
#include <sstream>
using namespace std;
// ... ...
ifstream file("file.txt",ios::in);
if (file.good())
{
string str;
while(getline(file, str))
{
istringstream ss(str);
int num;
while(ss >> num)
{
// ... you now get a number ...
}
}
}
You need to read Why is iostream::eof inside a loop condition considered wrong?.
回答by Some programmer dude
As for reading until the end of the line. there's std::getline.
至于读到行尾。有std::getline。
You have another problem though, and that is that you loop while (!file.eof())which will most likely not work as you expect. The reason is that the eofbitflag is not set until afteryou try to read from beyond the end of the file. Instead you should do e.g. while (std::getline(...)).
但是，您还有另一个问题，那就是您的循环while (!file.eof())很可能不会按您的预期工作。原因是eofbit直到您尝试从文件末尾读取之后才设置该标志。相反，你应该做 eg while (std::getline(...))。
回答by Rakia
char eoln(fstream &stream) // C++ code Return End of Line
{
if (stream.eof()) return 1; // True end of file
long curpos; char ch;
curpos = stream.tellp(); // Get current position
stream.get(ch); // Get next char
stream.clear(); // Fix bug in VC 6.0
stream.seekp(curpos); // Return to prev position
if ((int)ch != 10) // if (ch) eq 10
return 0; // False not end of row (line)
else // (if have spaces?)
stream.get(ch); // Go to next row
return 1; // True end of row (line)
} // End function
回答by Rakia
If you want to write it as function in order to call some where, you can use a vector. This is a function which I use to read such file and return integers element wise.
如果你想把它写成函数以便调用一些地方，你可以使用向量。这是我用来读取此类文件并明智地返回整数元素的函数。
vector<unsigned long long> Hash_file_read(){
int frames_sec = 25;
vector<unsigned long long> numbers;
ifstream my_file("E:\Sanduni_projects\testing\Hash_file.txt", std::ifstream::binary);
if (my_file) {
//ifstream file;
string line;
for (int i = 0; i < frames_sec; i++){
getline(my_file, line);
numbers.push_back(stoull(line));
}
}
else{
cout << "File can not be opened" << endl;
}
return numbers;
}
