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法律研究使用seekg()在 C++ 語言檔案處理中設定位置
seekg() 是 iostream 庫中的一項函式，允許我們在檔案中尋求任意位置。它主要用於設定要從 C++ 檔案處理中的給定檔案所提取的下一個字元的位置。
語法
istream&seekg(streamoff offset, ios_base::seekdir dir); istream&seekg(streampos position); Where, position: It is the new position in the stream buffer. offset: It is an integer value of type streamoff which represents the offset in the stream’s buffer, relative to the dir parameter. dir: It is the seeking direction. It is an object of type ios_base::seekdir that can take any offset constant value. Three direction used for offset values are: ios_base::beg = from the beginning of the stream’s buffer. ios_base::cur = from the current position in the stream’s buffer. ios_base::end = from the end of the stream’s buffer.
所需步驟和操作
Begin Open a data file for input/output operations. Add ‘TutorialsPoint’ to the file. Seek to 9 position from beginning of the file. Read the next 5 characters from the file into buffer F. End F with null character as terminator character. Print the contents. Close the file. End
示例
#include <fstream>
#include <iostream>
using namespace std;
int main (int argc, char** argv) {
fstream File("d.txt", ios::in | ios::out );
File << "TutorialsPoint";
File.seekg(9, ios::beg);
char F[9];
File.read(F, 5);
F[5] = 0;
cout <<F<< endl;
File.close();
}輸出
Point
更新時間：30-Jul-2019
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