假設有一個叫 data.txt 的檔案, 它包含以下内容:
Fry: One Jillion dollars.
[Everyone gasps.]
Auctioneer: Sir, that's not a number.
資料讀取, 測試 。
以下就是基于 data.txt 的資料讀取操作:
#include
#include
#include
using namespace std;
//輸出空行
void OutPutAnEmptyLine()
{
cout<<"\n";
}
//讀取方式: 逐詞讀取, 詞之間用空格區分
//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;
}
}
//讀取方式: 逐行讀取, 将行讀入字元數組, 行之間用回車換行區分
//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;
}
}
//讀取方式: 逐行讀取, 将行讀入字元串, 行之間用回車換行區分
//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;
}
}
//帶錯誤檢測的讀取方式
//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(); //逐詞讀入字元串
OutPutAnEmptyLine(); //輸出空行
ReadDataFromFileLBLIntoCharArray(); //逐詞讀入字元數組
OutPutAnEmptyLine(); //輸出空行
ReadDataFromFileLBLIntoString(); //逐詞讀入字元串
OutPutAnEmptyLine(); //輸出空行
ReadDataWithErrChecking(); //帶檢測的讀取
return 0;
}
輸出結果為:
ead from file: Fry:
ead from file: One
ead from file: Jillion
ead from file: dollars.
ead from file: [Everyone
ead from file: gasps.]
ead from file: Auctioneer:
ead from file: Sir,
ead from file: that's
ead from file: not
ead from file: a
ead from file: number.
ead from file: 資料讀取,
ead from file: 測試
ead from file: 。
Read from file: Fry: One Jillion dollars.
ead from file: [Everyone gasps.]
ead from file: Auctioneer: Sir, that's not a number.
ead from file: 資料讀取, 測試 。
Read from file: Fry: One Jillion dollars.
ead from file: [Everyone gasps.]
ead from file: Auctioneer: Sir, that's not a number.
ead from file: 資料讀取, 測試 。
Error opening dataFUNNY.txt for input
Press any key to continue
轉自:http://www.cnblogs.com/JCSU/articles/1190685.html