int main( fstream outFile(numbers. txt", ios: out ) int nums33]={1234,3,567,34,8,6789,124,2345,89}; for( int row=0;row<3;row++)∥向文件输出三行 for(int col=0; col<3; col++) outFile < setw(10)<< numsrowllcol < out File < endl outFile. close(; return U; 2-5. cpp
int main( ) { fstream outFile("numbers.txt", ios::out ); int nums[3][3] = { 1234, 3, 567, 34, 8, 6789, 124, 2345, 89 } ; for( int row = 0 ; row < 3 ; row++ ) // 向文件输出三行 { for( int col = 0 ; col < 3 ; col++ ) outFile << setw(10) << nums[row][col] <<" " ; outFile << endl ; } outFile.close( ); return 0; } 2-5.cpp
233采用>>从文件读数据 例2-6 #include <iostream> using namespace std; #include <fstream> #include <estdllib> void maino fstream dataFile char name 81;
17 2.3.3 采用 >> 从文件读数据 • 例2-6 #include <iostream> using namespace std; #include <fstream> #include <cstdlib> void main( ) { fstream dataFile; char name [81];
data file open( demofile txt", ios: in); if (!data File) cout << File open error!"<< endl; exit(o for(int count =0; count <4; count++) dataFile > name cout < name < endl: data File close(; 2-6.cpp
dataFile.open("demofile.txt", ios::in); if ( !dataFile) { cout << "File open error!" << endl; exit(0); } for(int count = 0; count < 4; count++) { dataFile >> name; cout << name << endl; } dataFile.close( ); } 2-6.cpp
234检测文件结束 eof()成员函数报告文件结尾 Note:“ end of file”意味着文件指针已经超出了最 后一个数据的范围,无数据可读 while(! in file eof o : if (in File eof) in File >>var; in File close(; ………
19 2.3.4 检测文件结束 • eof ( ) 成员函数报告文件结尾。 • Note: “end of file” 意味着文件指针已经超出了最 后一个数据的范围，无数据可读. while( ! inFile.eof ( )) inFile >> var; if (inFile. eof ( )) inFile.close( );
例27对例2-6的改进。 void main() ●●●● // open file while(! data File. eof() data File > name i if(data File. fail) break. cout<<name<<"ln"’; data File close(; 2-7.cpp
void main( ) { …… // open file while( ! dataFile.eof( )) { dataFile >> name ; if(dataFile.fail( )) break; cout << name << "\n"; } dataFile.close( ); } 例2-7 对例2-6 的改进。 2-7.cpp