如何使用istream_iterator將文字檔轉到vector? (C/C++) (STL)
stream_iterator除了能使用cin外,只要是stream都可用,如fstream,stringstream都可用。本範例demo如何利用stream_iterator將文字檔的每個單字轉到vector內。
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/*
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(C) OOMusou 2006 http://oomusou.cnblogs.com
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Filename : StreamIteratorInFileOutFile.cpp
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Compiler : Visual C++ 8.0 / ISO C++
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Description : Demo how to use istream_iterator from file to vector
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and ostream_iterator from vector to file
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Release : 12/07/2006
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*/
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#include <fstream>
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#include <iostream>
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#include <vector>
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#include <algorithm>
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#include <string>
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#include <iterator>
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using namespace std;
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int main() {
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ifstream inFile("books-11-30-2006.txt");
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vector<string> svec;
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// Copy cin to vector
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copy(istream_iterator<string>(inFile), istream_iterator<string>(), back_inserter(svec));
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// Sort vector
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sort(svec.begin(), svec.end());
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// Copy vector to cout
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ofstream outFile("books-11-30-2006_r.txt");
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copy(svec.begin(), svec.end(), ostream_iterator<string>(outFile,"\n"));
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inFile.close();
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outFile.close();
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}
/* 2
(C) OOMusou 2006 http://oomusou.cnblogs.com3

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Filename : StreamIteratorInFileOutFile.cpp5
Compiler : Visual C++ 8.0 / ISO C++6
Description : Demo how to use istream_iterator from file to vector7
and ostream_iterator from vector to file8
Release : 12/07/20069
*/10

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#include <fstream>12
#include <iostream>13
#include <vector>14
#include <algorithm>15
#include <string>16
#include <iterator>17

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using namespace std;19

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int main() {21
ifstream inFile("books-11-30-2006.txt");22
vector<string> svec;23

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// Copy cin to vector25
copy(istream_iterator<string>(inFile), istream_iterator<string>(), back_inserter(svec));26

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// Sort vector28
sort(svec.begin(), svec.end());29

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// Copy vector to cout31
ofstream outFile("books-11-30-2006_r.txt");32
copy(svec.begin(), svec.end(), ostream_iterator<string>(outFile,"\n"));33

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inFile.close();35
outFile.close();36
}
使用這種寫法,優點是程式碼非常精簡,但缺點是一定得用一個Container接,如vector,實務上可能邊讀文字檔邊處理就好。
Keyword
stream_iterator, copy, vector, text


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