假设有一个叫 data.txt 的文件, 它包含以下内容: ![使用ifstream和getline读取文件内容[c++] - zhuandi_h - scholar_fish](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
Fry: One Jillion dollars.[Everyone gasps.]Auctioneer: Sir, that's not a number.数据读取， 测试 。 以下就是基于 data.txt 的数据读取操作: #include <iostream>#include <fstream>#include <string>using namespace std;//输出空行void OutPutAnEmptyLine()![使用ifstream和getline读取文件内容[c++] - zhuandi_h - scholar_fish](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
{ ![使用ifstream和getline读取文件内容[c++] - zhuandi_h - scholar_fish](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
cout<<"\n";![使用ifstream和getline读取文件内容[c++] - zhuandi_h - scholar_fish](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}//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 ) ![使用ifstream和getline读取文件内容[c++] - zhuandi_h - scholar_fish](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
{ cout << "Read from file: " << s << endl; ![使用ifstream和getline读取文件内容[c++] - zhuandi_h - scholar_fish](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}}//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 stringsvoid 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 occurredvoid ReadDataWithErrChecking(){ string filename = "dataFUNNY.txt"; ifstream fin( filename.c_str()); if( !fin ) { cout << "Error opening " << filename << " for input" << endl; exit(-1); }}int main(){
Fry: One Jillion dollars.[Everyone gasps.]Auctioneer: Sir, that's not a number.数据读取， 测试 。 #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 stringsvoid 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 occurredvoid 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;
}
输出结果为:Read from file: Fry:Read from file: OneRead from file: JillionRead from file: dollars.Read from file: [EveryoneRead from file: gasps.]Read from file: Auctioneer:Read from file: Sir,Read from file: that'sRead from file: notRead from file: aRead from file: number.Read from file: 数据读取，Read from file: 测试Read from file: 。 Read from file: Fry: One Jillion dollars.Read from file: [Everyone gasps.]Read from file: Auctioneer: Sir, that's not a number.Read from file: 数据读取， 测试 。Read from file: Fry: One Jillion dollars.Read from file: [Everyone gasps.]Read from file: Auctioneer: Sir, that's not a number.Read from file: 数据读取， 测试 。Error opening dataFUNNY.txt for inputPress any key to continue