#include <fstream>
#include <string>
// inside of main...
ifstream fin;
string inFile = "test.dat"
fin.open(inFile.c_str(), ios::in | ios::binary);
// Now I want to use seekg() and read() to acquire the substring
// "wor" from "Hello,world!". NOTE: In understand there are easier
// ways of doing this but I want to use seekg/read specifically.
fin.seekg(6, ios_base::beg);
fin.read((char*)temp_str, 3);
fstream seekg() and read()
Author
(Cplusplus)
I need to perform "random access" on a data file I am using; meaning that I need to be able to specify any arbitrary place in the file and read data at that point.
I am working with a binary file, and so have used ios::binary when opening the file reader.
I understand how to use seekg(int, ios_base::seekdir) to move the read marker in conjunction with read(char*,int) to specify how many characters to read at the read marker's location... i'm just getting caught up in some technical details here.
Say I have a string of 12 characters, "Hello,world!", that I want to read. Also assume 1-byte characters in accordance with ASCII.
Would this code result with storing "wor" into temp_str?
What is confusing me is this: I am not sure how to "translate" seekg and read. To me, the line fin.seekg(6, ios_base::beg) says "Move the read pointer 6 units to the right of the beginning of the file" (since 'w' is the 7th character). And the line fin.read(/* ... */) says "Beginning with the current character/byte in the file, read 3 characters without moving the read pointer."
I can't download a C++ compiler right now and check this out for myself. Please let me know if I am on track or if I am slightly misinformed...
-ply
You might want to try googleing std:fstream and that may answer your questions on its own. :) check out msdn thats a good resource.
Regards Jouei
Regards Jouei
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
