The cout statement in this for loop:
for (vector<Student>::iterator qw = students.begin(); qw != students.end(); ++qw){
Student a = *qw;
name = a.getName();
regno = a.getRegNo();
std::cout << "Name: "<< name << " Reg Number: " << regno << endl;
}
Is creating some odd behavior, what the cout should print is something like this:
Name: Mike Sanderson Reg Number: 10101
However which it actually prints out it:
Reg Number: 10101on
It would seem to me that after the second part of the cout statement it is going back to the start of the line and overwriting itself, but why?
Hope you guys can help me and if you need more info let me know!
This is what the carriage return character does (that is, \r in a string literal). I assume name string has an \r at the end of it. You'll need to figure out how it got there and remove it.
I'm guessing that perhaps you read the names from a file, and that file was created on Windows, which ends lines with \r\n by default. C++ will usually handle the conversion between line endings for you when reading from a text file, but if you're reading the file as a binary file and using \n as a delimiter, you'll have this problem. The \r will be read as though it were part of the line.
Related
i have this project due however i am unsure of how to parse the data by the word, part of speech and its definition... I know that i should make use of the tab spacing to read it but i have no idea how to implement it. here is an example of the file
Recollection n. The power of recalling ideas to the mind, or the period within which things can be recollected; remembrance; memory; as, an event within my recollection.
Nip n. A pinch with the nails or teeth.
Wodegeld n. A geld, or payment, for wood.
Xiphoid a. Of or pertaining to the xiphoid process; xiphoidian.
NB: Each word and part of speech and definition is one line in a text file.
If you can be sure that the definition will always follow the first period on a line, you could use an implementation like this. But it will break if there are ever more than 2 periods on a single line.
string str = "";
vector<pair<string,string>> v; // <word,definition>
while(getline(fileStream, str, '.')) { // grab line, deliminated '.'
str[str.length() - 1] = ""; // get rid of n, v, etc. from word
v.push_back(make_pair<string,string>(str,"")); // push the word
getline(fileStream, str, '.'); // grab the next part of the line
v.back()->second = str; // push definition into last added element
}
for(auto x : v) { // check your results
cout << "word -> " << x->first << endl;
cout << "definition -> " << x->second << endl << endl;
}
The better solution would be to learn Regular Expressions. It's a complicated topic but absolutely necessary if you want to learn how to parse text efficiently and properly:
http://www.cplusplus.com/reference/regex/
This is a part of my code. I don't know why the string was partially overwrite by another string.
for(int xd = 0 ; xd < 10; xd++)
{
if(booklist[xd].length() != 0)
{
string d = string(booklist[xd]);
string e = "1,2,3,4";
string f = d + e;
cout << d.length() << endl;
cout << d << endl;
cout << f.length() << endl;
cout << f << endl;
}
}
The result of this code is:
16
brave new world
23
1,2,3,4ew world
28
nineteen eighty-four (1984)
35
1,2,3,4n eighty-four (1984)
I don't know why i got this wrong result.
Could someone help me?
Are you populating booklist by pulling from a file that you copied from Windows to a linux machine?
Windows will add a carriage return '\r' to the end of each line in addition to a newline. If you're reading from a windows file and using getline, it'll pull the carriage return into the string.
When a carriage return is output in the terminal, it resets the cursor to the beginning of the line, which would result in the behavior you're seeing.
To fix this, see this question on trimming whitespace from a string. The function you're looking for from that answer is rtrim (or "right trim"):
// trim from end (in place)
static inline void rtrim(std::string &s) {
s.erase(std::find_if(s.rbegin(), s.rend(), [](int ch) {
return !std::isspace(ch);
}).base(), s.end());
}
It's likely that your booklist entries have trailing carriage returns, causing line 4 (for instance) to print brave new world, return to column 1, and print 1,2,3,4 over it. (That's why the character count is greater on line 3 than line 1, despite the two lines having the same apparent length.)
Strip the trailing whitespace from booklist entries (or figure out why it's getting in there in the first place, and deal with that) and things should be fine.
Yes i got the reason why it shows wrong.
Just like what scohe001 said: when i use getline to put the file in to an array, it will add \r after each element, so i use substr to remove the \r .Now it get work. Thanks every one.
Wanting to do some fancy formatting. I have several lines that I want to interact with each other. Get the first two lines. Print out the character in the second line times the integer in the first line. Seperate them all with a asterisk character. No asterisk after the final character is printed. Move onto the next integer and character. Print them on a separate line. Do this for the whole list. The problem I am having is printing them on separate lines. Example:
5
!
2
?
3
#
Desired output:
!*!*!*!*!
?*?
#*#*#
My output:
!*!*!*!*!*?*?*#*#*#*
Below is my code. Another thing to mention is that I am reading the data about the characters and numbers from a separate text file. So I am using the getline function.
Here is a chunk of the code:
ifstream File
File.open("NumbersAndCharacters.txt")
string Number;
string Character;
while(!File.eof(){
getline(File, Number);
getline(File, Character);
//a few lines of stringstream action
for (int i=0; i<=Number; i++){
cout<<Character<<"*";}//end for. I think this is where
//the problem is.
}//end while
File.close();
return 0;
Where is the error? Is it the loop? Or do I not understand getline?
It should be printing an "endl" or "\n" after each multiplication of the character is done.
Thanks to everyone for the responses!
You have not shown your code yet, but what seems to be the issue here is that you simply forgot to add a new line every time you print your characters. For example, you probably have done:
std::cout << "!";
Well, in this context you forgot to add the new line ('\n'), so you have two options here: first insert the new line yourself:
std::cout << "! \n";
Or std::endl;
std::cout << "!" << std::endl;
For comparison of the two, see here and here. Without further description, or more importantly your code that doesn't seem to work properly, we can't make suggestions or solve your problem.
Using fstreams I have a file opened that contains numerous lines. Each contiguos set of 4 lines are such that: the first line is an int, the second and third are strings and fourth is a double. This sequence continues till EOF.
I'm attempting to load these lines into a struct array:
struct Library {
int id;
string title;
string artist;
double price;
};
and the code I'm trying to implement to load data into the struct is this:
const int LIMIT = 10
Library database[LIMIT];
ifstream file;
file.open("list.txt");
if(file) {
while(!(file.eof()) && counter < LIMIT) {
file >> database[counter].id;
getline(file, database[counter].title;
getline(file, database[counter].artist;
file >> database[counter].price;
}
} else {
...
}
// Using the following to debug output
for(int i = 0; i < counter; i++) {
cout << "ID: " << database[i].id << endl
<< "Title: " << database[i].title << endl
<< "Artist: " << database[i].artist << endl
<< "Price: " << database[i].price << endl
<< "-----------------------" << endl;
}
The file I'm trying to throw at this thing is
1234
Never Gonna Give You Up
Rick Astley
4.5
42
Thriller
Michael Jackson
32.1
The problem I'm having here is that between reading the id and title using file >> ... and getline(...) is that somewhere a newline bite is being introduced screwing up the output, which displays this monstrosity...
ID: 1234
Title:
Artist: Never Gonna Give You Up
Price: 0
--------------------
ID: 0
Title:
Artist:
Price: 0
--------------------
The solution is probably the most basic of solutions, but mainly because I can't figure out exactly what is going on with the newline bite I can't combobulate a phrase to shove into google and do my stuff there, and I'm at the stage where I've been looking at a problem so long, basic knowledge isn't working properly - such as how to handle basic input streams.
Any form of help would be much appreciated! Thanks in advance :)
This happens because the >> operator for the input stream only grabs part of a line, and does not always grab the newline character at the end of the line. When followed by a call to getline, the getline will grab the rest of the line previously parsed, not the line after it. There are a few ways to solve this: you can clear the buffer from the input stream after each read, or you can simply get all your input from getline and just parse the resulting strings into an integer or a double when you need to with calls to stoi or stod.
As a side note, you don't want to detect the end of your file the way you presently are. See why is eof considered wrong inside a loop condition?
You can solve this problem by adding:
fflush(file);
everytime before you use getline(file, ...). Basically this will clear the input buffer before you use the getline() function. And fflush() is declared in the cstdio library.
file >> database[counter].id;
will read, in this case, a whitespace separated sequence of characters that is interpreted as an int. The newline is considered whitespace. You should now be sitting on that newline character, thus the getline() will read nothing -- successfully -- and increment the file position just past that.
You may be better off using getline() for each line and then separately interpreting the lines from the reading. For example, the first line read could be interpreted with a subsequent std::stoi() to get the integer representation from the string.
In C++, Ubunt 12.04, I have a file named config.txt which contains user name and password. I have 2 public static string variables: USER and PASSWORD. This is my code:
// Read file from config
string text[2];
int count = 0;
while(!fin.eof()){
getline(fin,text[count]);
count++;
if(count == 2){
break;
}
}
CONNECTOR::USER = text[0];
CONNECTOR::PASSWORD = text[1];
string userAndPassword = CONNECTOR::USER + ":" + CONNECTOR::PASSWORD;
cout << CONNECTOR::USER << endl; // It's fine, right user: qsleader
cout << CONNECTOR::PASSWORD << endl; // ok, right password: 123456
cout <<"user and password: " << userAndPassword << endl; // It's weird text! Problem here!
The weird text result is: :123456d password: qsleader!! This is not what I expected! But I don't know why this happen? Can anyone give me an suggestion? (If i print: cout << "user and password: qsleader:123456", the result is good!!)!
The problem is created when you read the values. Indeed, I guess that your file has the two items on two different lines. Furthermore, I guess this file uses Windows line endings. Therefore, when you read the first item, it reads qsleader\r and then stops as the next extracted character is \n, extracted but not appended to the string.
When you create the userAndPassword string, it is in fact qsleader\r:123456. This special character \r is a return carriage. It makes the cursor go to the beginning of the line. Therefore, on the last line, you first output user and password: qsleader, then go back to the first column, and write :123456, resulting in :123456d password: qsleader.
You are setting userAndPassword to a hellish expression involving assignments. I guess your intent was:
string userAndPassword = CONNECTOR::USER + ":" + CONNECTOR::PASSWORD