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+---- Thread: [C] 1 small error... anyone know how to fix this? (/showthread.php?tid=5152920)
1 small error... anyone know how to fix this? - Aus10 - Jan 30, 2016
I've looked everywhere on how to fix this. From my understanding, the error means that the word " open " simply will not work for the line of code. I have put dashes to the right of the specific line of code that breaks the program. Any thoughts guys?
Code
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;
bool openFileIn(fstream &, string);
void read_questions(fstream &);
int main()
{
fstream fin;
if (openFileIn(fin, "questions.txt"))
{
cout << "File opened.\n";
cout << "Now reading data from the file.\n\n";
read_questions(fin);
fin.close();
cout << "\nDone.\n";
}
else
cout << "File open error!" << endl;
return 0;
}
bool openFileIn(fstream &fin, string name)
{
fin.open(name, ios::in); <---------------------------------------------------
if (fin.fail())
return false;
else
return true;
}
void read_questions(fstream &fin)
{
string line;
while (fin >> line)
{
cout << line << endl;
}
}* - abratar - Jan 30, 2016
I tested it with your code and it is working... Only the output is only 1 word each line but you can fix that. Any Error Message?
* - Aus10 - Jan 30, 2016
In function 'bool openFileIn(std::fstream&, std::string)':|
error: no matching function for call to 'std::basic_fstream<char>::open(std::string&, const openmode&)'|
note: candidate is:|
note: void std::basic_fstream<_CharT, _Traits>::open(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::ios_base::openmode = std::_Ios_Openmode]|
note: no known conversion for argument 1 from 'std::string {aka std::basic_string<char>}' to 'const char*'|
||=== Build failed: 1 error(s), 0 warning(s) (0 minute(s), 0 second(s)) ===|
This is what I get when I run it. Thanks for your help.
Also if it is only the first word on each line, how can I fix that? Maybe a for loop using getline? Little rusty on combining loops with getlines :P
* - Goodies - Jan 30, 2016
It compiles and runs fine for me. Although I do see the error.
fin.open() looks like it is expecting a const char* and you're giving it a string. I'm not sure why, actually, but try this:
PHP Code
<?php
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;
inline bool openFileIn(fstream &, const string&);
void read_questions(fstream &);
int main(){
fstream fin;
if (openFileIn(fin, "questions.txt")){
cout << "File opened.\nNow reading data from the file.\n\n";
read_questions(fin);
fin.close();
cout << "\nDone.\n";
}
else
cout << "File open error!" << endl;
return 0;
}
inline bool openFileIn(fstream &fin, const string &name){
fin.open(name.c_str(), ios::in);
if (fin.fail())
return false;
return true;
}
void read_questions(fstream &fin){
string line;
while (fin >> line){
cout << line << endl;
}
}
I use K&R, sorry. Hate that newline after functions/loops/ifs/etc...
* - 0xDEAD10CC - Jan 30, 2016
It works only if you are compiling as C++11 or newer. This prototype was only introduced in C++11:
Code
std::basic_filebuf<CharT, Traits>* open( const std::string& str, std::ios_base::openmode mode );Older standards, you can only open with a C-string (const char *), and not std::string (std::basic_string<char>).
Hence, the reason why it worked for abratar, he was using C++11, and I would assume that OP is using GCC, or some port of it, and not passing any command line flags to allow it to be compiled via a newer standard. std::basic_string<char>::c_str() is the solution here unless you're using C++11/14.
* - Aus10 - Jan 30, 2016
You fellas are much smarter then I. Thank you for your help, it worked! My program now shows the whole txt file one word at a time lol... Trying to get it to show normally with no end lines.
of
the
following
is
NOT
a
reason
for
writing
functions?
modularity
reusability
easier
testing
and
verification
reduced
code
size
I've been messing around with end lines and for loops, however they dont fix it lol.. scared to stray too far from this set up and losing my progress.
* - Goodies - Jan 30, 2016
(Jan 30, 2016 07:19 PM)Aus10 Wrote: You fellas are much smarter then I. Thank you for your help, it worked! My program now shows the whole txt file one word at a time lol... Trying to get it to show normally with no end lines.
of
the
...
code
size
I've been messing around with end lines and for loops, however they dont fix it lol.. scared to stray too far from this set up and losing my progress.
You can use something like (in your read_questions function):
PHP Code
<?php
std::string line;
line.erase(std::remove(line.begin(), line.end(), '\n'), line.end());
It's probably not the best way, but it will definitely work and I think it's what you have to use with the way you have it.
If you don't want that, use std::getline instead of fstream >> std::string.
* - 0xDEAD10CC - Jan 30, 2016
Show normally with no endlines? What does that mean? Extracting from a stream by default should skip whitespace.
* - Goodies - Jan 30, 2016
(Jan 30, 2016 10:19 PM)0xDEAD10CC Wrote: Show normally with no endlines? What does that mean? Extracting from a stream by default should skip whitespace.
@OP this. You're printing it with:
cout << line << endl; omit that endl.
* - Aus10 - Jan 31, 2016
I tried that Goodies :P I took away the endl; and just ended it after line, but then it puts it all down on the same line from left to right in the prompt.( Which is bad) Because the user would not be able to see all of it without scrolling right. :) By show normally, I just meant output in the same format as the .txt file that it's in. If we can imagine taking a multiple choice test, with 4 answers choices underneath each question. ^^ To your first post Goodies, I will have to try that now. Will post back when I have tried it. Thanks!
I found one proper way to use the getline function, the problem with white space can be solved by the getline function. The function reads a line of data, including white space characters. Here is an example of the function call:
PHP Code
<?php
getline(fin, str, '\n');
fin : This is the name of the file stream object, it specifies the stream object from which the data is to be read.
str : This is the name of the string object. the data read from the file will be stored here.
'\n' : This is a delimiter character of choice. If this delimiter is encountered, it will cause the function to stop reading. (This is optional. If it's left out, '\n' is the default).
* - 0xDEAD10CC - Jan 31, 2016
Quote: I just meant output in the same format as the .txt file that it's in.
Well then you need to keep track of where each newline, tab, space, etc... are within that file otherwise there's no way to tell. Why not just read the file and print out the file contents rather than retrieving individual tokens delimited by the whitespace? You can use std::istream::read() to read back the exact bytes of the file without using anything as a delimiter, not even a newline.
* - Aus10 - Jan 31, 2016
I was able to read everything into the program this way.
PHP Code
<?php
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;
void read_questions(fstream &);
int main()
{
fstream fin;
string input;
fin.open("questions.txt", ios::in);
read_questions(fin);
return 0;
}
void read_questions(fstream &fin)
{
string input;
if (fin)
{
getline(fin, input);
while (fin)
{
cout << input << endl;
getline(fin, input);
}
fin.close();
}
}
It outputted like this:
Where does a C++ program begin its execution?
The first function in the file
The first function by alphabetic order of names
The function main( )
The function specified in the #DEFINE FirstFunction
How many values can be returned from a function by means of the "return" statement?
1
2
3
Lots and Lots
Which loop type is guaranteed to execute at least once?
for
while
do...while
all the above
Arrays are passed to functions by:
reference
value
either method
neither method
Global variables should be used...
in place of function parameters
only when absolutely needed
never
only during the full moon
When storing a floating point value to an integer type variable, the fractional part is:
rounded up
rounded down
branched
truncated
Which of the following is NOT a reason for writing functions?
modularity
reusability
easier testing and verification
reduced code size
Process returned 0 (0x0) execution time : 0.035 s
Press any key to continue.
Now I need to figure out how to "A" "B" "C" "D" Before each answer choice for every question. I'm thinking a basic for loop will work. Will update when I figure it out. =)
Update:
Changed EVERYTHING. UGH.
Couldn't get ABCD to show for each question using a while loop, so i switched to for loop. Here is what I did.
PHP Code
<?php
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;
// Function Prototype
void read_questions();
int main()
{
// fstream fin; // File stream input
// string question; // To hold file input
// Opening the file in input mode
// fin.open("questions.txt", ios::in);
read_questions();
return 0;
}
void read_questions()
{
string question;
string choice1;
string choice2;
string choice3;
string choice4;
string space;
fstream fin;
fin.open("questions.txt");
for (int x = 0; x < 7; x++)
{
getline(fin, question);
getline(fin, choice1);
getline(fin, choice2);
getline(fin, choice3);
getline(fin, choice4);
getline(fin, space);
cout << question << endl;
cout << "A: " << choice1 << endl;
cout << "B: " << choice2 << endl;
cout << "C: " << choice3 << endl;
cout << "D: " << choice4 << endl;
cout << space << endl;
}
Here is the result thus far:
Where does a C++ program begin its execution?
A: The first function in the file
B: The first function by alphabetic order of names
C: The function main( )
D: The function specified in the #DEFINE FirstFunction
How many values can be returned from a function by means of the "return" statement?
A: 1
B: 2
C: 3
D: Lots and Lots
Which loop type is guaranteed to execute at least once?
A: for
B: while
C: do...while
D: all the above
Arrays are passed to functions by:
A: reference
B: value
C: either method
D: neither method
Global variables should be used...
A: in place of function parameters
B: only when absolutely needed
C: never
D: only during the full moon
When storing a floating point value to an integer type variable, the fractional part is:
A: rounded up
B: rounded down
C: branched
D: truncated
Which of the following is NOT a reason for writing functions?
A: modularity
B: reusability
C: easier testing and verification
D: reduced code size
Process returned 0 (0x0) execution time : 0.028 s
Press any key to continue.
UPDATE: Now I put it through an array to handle the ABCD and have it stored into a 2D array.
PHP Code
<?php
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;
// Function Prototype
void read_questions();
int main()
{
read_questions();
return 0;
}
void read_questions()
{
string question;
string choice1;
string choice2;
string choice3;
string choice4;
string space;
fstream fin;
string input_arr[50][50];
fin.open("questions.txt");
for (int q = 0; q < 7; q++)
{
getline(fin, question);
getline(fin, choice1);
getline(fin, choice2);
getline(fin, choice3);
getline(fin, choice4);
getline(fin, space);
input_arr[q][0] = question;
input_arr[q][1] = "A. " + choice1;
input_arr[q][2] = "B. " + choice2;
input_arr[q][3] = "C. " + choice3;
input_arr[q][4] = "D. " + choice4;
input_arr[q][5] = space;
cout << input_arr[q][0] << endl;
cout << input_arr[q][1] << endl;
cout << input_arr[q][2] << endl;
cout << input_arr[q][3] << endl;
cout << input_arr[q][4] << endl;
cout << input_arr[q][5] << endl;
}
}
* - Russ. - Jan 31, 2016
^^ That looks like a thread. Problem solved mate?
* - Aus10 - Jan 31, 2016
So I've basically made this a blog lol.
New update, last update for a day or two.
Added the read_answers function, soon going to have the program compare the users answer choice to the correct answers in the .txt file.
PHP Code
<?php
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;
// Function Prototype
double read_questions();
double read_answers();
int main()
{
read_questions();
read_answers();
return 0;
}
double read_questions()
{
string question;
string choice1;
string choice2;
string choice3;
string choice4;
string space;
fstream fin;
string input_arr[50][50];
fin.open("questions.txt");
for (int q = 0; q < 7; q++)
{
getline(fin, question);
getline(fin, choice1);
getline(fin, choice2);
getline(fin, choice3);
getline(fin, choice4);
getline(fin, space);
input_arr[q][0] = question;
input_arr[q][1] = "A. " + choice1;
input_arr[q][2] = "B. " + choice2;
input_arr[q][3] = "C. " + choice3;
input_arr[q][4] = "D. " + choice4;
input_arr[q][5] = space;
cout << input_arr[q][0] << endl;
cout << input_arr[q][1] << endl;
cout << input_arr[q][2] << endl;
cout << input_arr[q][3] << endl;
cout << input_arr[q][4] << endl;
cout << input_arr[q][5] << endl;
}
}
double read_answers()
{
fstream fin;
char answer_arr[50];
char answer;
fin.open("answers.txt");
for (int y = 0; y < 7; y++)
{
fin >> answer;
answer_arr[y] = answer;
}
}
Yep lol problem solved. Thanks guys !! :) Just excited that the program is taking off. Don't really know why im updating it so much lol.