How to read text from a file with cstdio

Question

1.00/5 (1 vote)

See more:

I am trying to read text from a file but it doesn't read all the characters, could someone please identify the problem

Contents of Text.txt

Test

main.cpp

C++

#include<iostream>
#include<cstdio>

using namespace std;

int main(){
    FILE* file;
    file = fopen("C:/Text.txt", "r");
    fseek(file, 0, SEEK_END);
    long Size = ftell(file);
    cout << Size << endl;
    fseek(file, 0, SEEK_SET);
    char* buf = new char[Size];
    fgets(buf, Size, file);
    cout << buf << endl;
}

Output:

4
Tes

Posted 17-Apr-14 11:53am

Sicppy

Add a Solution

Comments

Sicppy 17-Apr-14 17:53pm

By the way, I realized I forgot to fclose(); it has been fixed.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Answer 1 · 2014-04-17T12:19:00

Solution 1

If foes not read all the characters because you are not trying to read them. You are seeking the end position. Remove that line, and the file will be opened in rewound position, at zero. Then read data in a single block or in a loop.

Also note that SEEK_END has no real standard portability. Better avoid using it:
http://www.cplusplus.com/reference/cstdio/fseek[^].

—SA

Posted 17-Apr-14 12:19pm

Sergey Alexandrovich Kryukov

Comments

Sicppy 17-Apr-14 18:49pm

Actually, the first fseek goes to the end byte, the ftell tells be where it is(giving me the size of the entire file) then I go back to the beginning, and use fgets to read the entirety of the file into a char*

Sergey Alexandrovich Kryukov 17-Apr-14 19:01pm

Just remove it and don't use with SEEK_END. If you really want to read something at the end first, review your file structure. Put all "metadata" in the very beginning.
Anyway, are you going to accept the answer formally (green "Accept" button)? I told you all you need.
—SA

Sicppy 17-Apr-14 19:07pm

No you haven't text files don't have meta, they're just an array of characters. Also, I'm not reading something at the end, I'm going to the end and then having it tell me where it is in the file so I know the size of the file, also, I've solved it myself, it actually gives me one less than the actual byte size for some reason.

Sergey Alexandrovich Kryukov 17-Apr-14 19:10pm

What are you even talking about? I told you exactly what to do. Don't go to the end, you did not give me any valid reason for doing that.
—SA

Sicppy 17-Apr-14 19:20pm

First of all, I go back to the beginning after going to the end. Second of all, I told you, the reason I go to the end, is to get the overall file size, if you go to the last byte in a file and read back where you are you will get the file size.

Sergey Alexandrovich Kryukov 17-Apr-14 20:10pm

I know, no need to repeat. You can do it (and then use ftell), but this is not a good idea.
—SA

Sicppy 17-Apr-14 21:01pm

Then how would you suggest I go about reading an entire text file?

Sergey Alexandrovich Kryukov 17-Apr-14 22:07pm

Up to down, sequentially. You have no reason to do anything else. Explain me what's the content, why do you need the size, and I'll explain you what to do.
And if the size (more typically, number of records) is really needed, it should be written in the beginning of the file, like in all humane formats.
—SA

Sicppy 18-Apr-14 0:37am

I'm loading a Wavefront(.obj) and unfortunately it does not have the number of records

Sicppy 18-Apr-14 0:37am

It doesn't have the number of records stored I mean

Sergey Alexandrovich Kryukov 18-Apr-14 1:56am

No matter what, format should be prefixed. Finding the size is a bad idea in principle.
—SA

Sicppy 18-Apr-14 11:30am

Well if it was up to me I would've made it prefixed, because using clunky ways to find the file size isn't exactly my idea of efficient, but this is the format specification: http://en.wikipedia.org/wiki/Wavefront_.obj_file

Sergey Alexandrovich Kryukov 18-Apr-14 11:46am

Ah, I see; you never told us where it's from.
But this document says it's a text file. Which you should read line by line top down anyway. The size cannot help...
—SA

Sicppy 18-Apr-14 11:49am

Sorry, I need to stop assuming things are common knowledge, I come from a background in 3D modeling where .obj is common knowledge

Sergey Alexandrovich Kryukov 18-Apr-14 11:51am

No problem. Yes, it's common, but you could have just mentioned it. Most general mistake is not telling us about some ultimate goals...
—SA

Sicppy 18-Apr-14 11:57am

Alright, well, anyways, I still need to know the best way to read the entire file.

Sergey Alexandrovich Kryukov 18-Apr-14 12:13pm

It really depends on what you are going to do with it. For example, is it small enough to read it all in memory? Do you need to content (I don't mean raw content, could be parsed) in memory?
—SA

Sicppy 18-Apr-14 12:26pm

I want to read and parse each line into memory using fscanf and cstdio

Sergey Alexandrovich Kryukov 18-Apr-14 13:29pm

Here you go. Read and parse line by line.
—SA

Sicppy 18-Apr-14 13:44pm

Was there supposed to be a link there?

Sergey Alexandrovich Kryukov 18-Apr-14 14:42pm

What link? You next problem is defining convenient data structure.
—SA

Sicppy 18-Apr-14 15:06pm

You said "Here you go" so I thought you were trying to give me a link or something

Sergey Alexandrovich Kryukov 18-Apr-14 15:10pm

I have no idea why would you think so. :-)
—SA

Sicppy 18-Apr-14 15:16pm

Well this is my current mesh.cpp but it just freezes in the LoadMesh function