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在 C++ 语言文件处理中使用 seekg() 设置位置

2023-06-20 10:38:03 519

seekg()是iostream库中的一个函数，它允许我们在文件中查找任意位置。它主要用于设置在C++文件处理中从给定文件的输入流中提取的下一个字符的位置。

语法

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.

所需的步骤和操作

Begin
   Open a data file for input/output operations.
   Add ‘nhooo’ 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 
#include 
using namespace std;
int main (int argc, char** argv) {
   fstream File("d.txt", ios::in | ios::out );
   File << "nhooo";
   File.seekg(9, ios::beg);
   char F[9];
   File.read(F, 5);
   F[5] = 0;
   cout <输出结果Point

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在 C++ 语言文件处理中使用 seekg() 设置位置

语法

示例

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