读一个std :: ifstream到一个向量的行 [英] Reading an std::ifstream to a vector of lines
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问题描述
我如何在一个文件中读取每行是一个数字,然后将该数字输出到一个向量行?
例如:file.txt包含:
314
159
265
123
456 $ b b
我尝试过这个实现:
vector< int> ifstream_lines(ifstream& fs){
vector< int>出口;
int temp;
getline(fs,temp);
while(!fs.eof()){
out.push_back(temp);
getline(fs,temp);
}
fs.seekg(0,ios :: beg);
fs.clear();
return out;
}
但是当我尝试编译时,我会得到如下错误:
错误C2784:'std :: basic_istream< _Elem,_Traits> & std :: getline
(std :: basic_istream< _Elem,_Traits>&,std :: basic_string< _Elem,_Traits,_Alloc>&)':
无法推导' std :: basic_istream< _Elem,_Traits> &'from'std :: ifstream'
因此,显然有些错误。有比我所想的更优雅的解决方案吗? (假设第三方库不支持Boost)
谢谢!
解决方案 p>我怀疑你想要这样的东西:
#include< vector&
#include< fstream>
#include
std :: vector< int>出口;
std :: ifstream fs(file.txt);
std :: copy(
std :: istream_iterator< int>(fs),
std :: istream_iterator< int>(),
std :: back_inserter (out));
How would I go about reading in a file where each line is a single number, then outputing that number into a vector of lines?
eg: file.txt contains:
314
159
265
123
456
I have tried this implementation:
vector<int> ifstream_lines(ifstream& fs) {
vector<int> out;
int temp;
getline(fs,temp);
while (!fs.eof()) {
out.push_back(temp);
getline(fs,temp);
}
fs.seekg(0,ios::beg);
fs.clear();
return out;
}
but when I attempt to compile, I get errors such as:
error C2784: 'std::basic_istream<_Elem,_Traits> &std::getline
(std::basic_istream<_Elem,_Traits> &,std::basic_string<_Elem,_Traits,_Alloc> &)' :
could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &' from 'std::ifstream'
so, obviously, something is wrong. Is there a more elegant solution than what I am trying? (Assuming 3rd party libraries like Boost are unavailable)
Thanks!
解决方案 I suspect you want something like this:
#include <vector>
#include <fstream>
#include <iterator>
std::vector<int> out;
std::ifstream fs("file.txt");
std::copy(
std::istream_iterator<int>(fs),
std::istream_iterator<int>(),
std::back_inserter(out));
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