from http://blog.csdn.net/xiaoguaihai/article/details/25735383 2014.05
有一次用到了C++ 读入文件的相关操作,看到又一篇文章写得比较好,转载给大家看看:希望对大家有帮助
假设读入的文件名为data.txt
- #include <iostream>
- #include <fstream>
- #include <string>
-
- using namespace std;
-
- //输出空行
- void OutPutAnEmptyLine()
- {
- cout<<"\n";
- }
-
- //读取方式: 逐词读取, 词之间用空格区分
- //read data from the file, Word By Word
- //when used in this manner, we'll get space-delimited bits of text from the file
- //but all of the whitespace that separated words (including newlines) was lost.
- void ReadDataFromFileWBW()
- {
- ifstream fin("data.txt");
- string s;
- while( fin >> s )
- {
- cout << "Read from file: " << s << endl;
- }
- }
-
- //读取方式: 逐行读取, 将行读入字符数组, 行之间用回车换行区分
- //If we were interested in preserving whitespace,
- //we could read the file in Line-By-Line using the I/O getline() function.
- void ReadDataFromFileLBLIntoCharArray()
- {
- ifstream fin("data.txt");
- const int LINE_LENGTH = 100;
- char str[LINE_LENGTH];
- while( fin.getline(str,LINE_LENGTH) )
- {
- cout << "Read from file: " << str << endl;
- }
- }
-
- //读取方式: 逐行读取, 将行读入字符串, 行之间用回车换行区分
- //If you want to avoid reading into character arrays,
- //you can use the C++ string getline() function to read lines into strings
- void ReadDataFromFileLBLIntoString()
- {
- ifstream fin("data.txt");
- string s;
- while( getline(fin,s) )
- {
- cout << "Read from file: " << s << endl;
- }
- }
-
- //带错误检测的读取方式
- //Simply evaluating an I/O object in a boolean context will return false
- //if any errors have occurred
- void ReadDataWithErrChecking()
- {
- string filename = "dataFUNNY.txt";
- ifstream fin( filename.c_str());
- if( !fin )
- {
- cout << "Error opening " << filename << " for input" << endl;
- exit(-1);
- }
- }
-
- int main()
- {
- ReadDataFromFileWBW(); //逐词读入字符串
- OutPutAnEmptyLine(); //输出空行
-
- ReadDataFromFileLBLIntoCharArray(); //逐词读入字符数组
- OutPutAnEmptyLine(); //输出空行
-
- ReadDataFromFileLBLIntoString(); //逐词读入字符串
- OutPutAnEmptyLine(); //输出空行
-
- ReadDataWithErrChecking(); //带检测的读取
- return 0;
- }
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