File streams, also known as file handles or file pointers, are a mechanism provided by the operating system to enable reading and writing of files. They can be used to perform sequential I/O (where data is read or written from the beginning to the end of the file) as well as random access I/O.

To perform random access I/O using file streams, you need to follow these steps:

1. Open the file: Open the file in the desired mode (read, write, or both) using the appropriate file stream objects or functions provided by your programming language. For example, in C++, you can use the fstream class to open a file:

std::fstream file;
file.open("example.txt", std::ios::in | std::ios::out);

1. Seek to the desired position: Use the seekg() and seekp() functions to set the position within the file where you want to read or write data. The seekg() function is used for input operations (reading), while the seekp() function is used for output operations (writing). Both functions take an offset and a seek direction as parameters. The std::ios::beg, std::ios::cur, and std::ios::end constants can be used to specify the seek direction relative to the beginning, current position, or end of the file, respectively. For example, to seek to the 100th byte in the file:

file.seekg(100, std::ios::beg); // Seek to the 100th byte from the beginning

1. Perform read or write operations: Once you’ve positioned the file stream to the desired location, you can perform read or write operations using the usual input/output functions provided by the programming language. For example, in C++, you can use the getline() function to read a line of text from the current position:

std::string line;
std::getline(file, line);

1. Close the file: After you’ve finished reading or writing from the file, it’s important to close the file stream using the appropriate function or method provided by your programming language. This step ensures that any resources associated with the file stream are properly released.

file.close();

Using file streams for random access I/O can be a powerful way to efficiently manipulate data in files. It allows you to read or write data at any position within a file, providing flexibility and performance advantages over sequential access methods.

#randomaccess #filestreams