So my text.txt looks like this:
208 84 Sally Goodnow 30:23 52 F Lancaster
209 344 Scott Grady 30:28 42 M Clinton
210 191 gail holland 30:36 52 F worcester
211 43 Karen Hughes 30:45 46 F Shirley
212 221 Edward m Powers Jr. 30:48 60 M Clinton
213 173 Lisa Zancewicz 30:49 34 F Clinton
214 186 Julianne Ryll 30:54 51 F Clinton
215 245 Briana Gibson 30:54 27 F Marlborough
my code to read the file looks like this:
int a;
int b;
string c;
string d;
string e;
string f;
string g;
string h;
string mystr;
int mymin;
int mysec;
int i;
int count=0;
while((infile>>a>>b>>c>>d>>e>>f>>g)&&getline(infile, h))
my code just breaks at line 212, I think it has to do with the name Edward m Powers Jr. (now I really hate this name, every time I look at it, lol). The name uses up my four strings, making h=60 M Clinton. Is is because string h cannot store integer 60 in it? I don't think that's the reason.
I'm doing the getline(infile, h) because I don't care about the name of town, Lancaster, Clinton are town names.
I tried to skip line 212, I did something like this:
string all
while(getline(infile, all)
{
if(all.at[0]!='2'&&all.at[1]!='1'&&all.at[2]!='2')
{
infile>>a>>b>>c>>d>>e>>f>>g;
getline(infile, h);
I'm doing this just to skip line 212, but it did not work. It just breaks at other lines.
It looks to me like at least half the input parsing questions here on stackoverflow.com have to do with the >> operator. I never liked using this operator. It has certain, rigid semantics affecting both input parsing and the input stream's error state, and unless the input matches the same semantics, using the >> operator will not work reliably.
And, adding insult to injury, in the real world the input is rarely a match for 100% of >>'s idiosyncrasies.
In this case, your problem is that you should not be using the >> operator at all. The >> operator is for parsing whitespace-delimited strings. You have correctly identified, more or less, where your problem is, now you just need to take one final step, to complete your training as a Jedi, and ditch the >> operator completely. You cannot easily use it to parse this kind of input.
Your input looks like a bunch of fixed-width fields. The fields always occupy the same character positions, on each line. That's what it looks to me. The >> operator is not meant to be used for parsing such input.
Rather, you should be reading the input one line at a time, using std::getline(), then using the substr() method to extract each field from its corresponding character positions. Then, for each individual field, trim the trailing whitespace, which is trivial.
P.S. You are not even using the >> operator on the right object. You're already using std::getline() to read each line of input, but then inexplicably use the >> operator on the input stream object anyway. That's wrong. You need to parse the line you have just read, rather than the following input in the file, by constructing a std::istringstream based on the line just read, then using the >> operator on that object. But, as I said, you should not be using the >> operator anyway...
Related
I don't know what happened to the post but it must have happened on my first edit.
I got this info to go in and work when it was in separate files. But I need it on one file.
I have looked in my text book and a bunch of other places but I can not find how to only get the text or characters out of the file.
I have got all the info into a single array but it looks like I will need to pull out each group piece by piece and put it where I want it but that looks slow, tedious and very susceptible to errors.
Johnson 85 83 77 91 76
Aniston 80 90 95 93 48
Cooper 78 81 11 90 73
Gupta 92 83 30 69 87
Blair 23 45 96 38 59
Clark 60 85 45 39 67
Kennedy 77 31 52 74 83
Bronson 93 94 89 77 97
Sunny 79 85 28 93 82
Smith 85 72 49 75 63
If this looks familiar it is the same assignment as my previous post, now I just need to figure out how to parse this info and use it again.
Chances are, you'll need to take your input as string value and check through it to find the beginning of the numerical characters.
only after having separated the alphabetical part of the input string from it's numerical part, you start creating your target arrays.
this might help: How can I check if a string has special characters in C++ effectively?
/e: wording
There are multiple ways of doing it. You could read it into a string and process it manually based on spaces. Or you could use stringstream to extract numerical values into array/vector. That however, still requires you to remove the name before you do it.
Here is a little code that reads the file content into an unordered_map which is essentially a dictionary as defined in other languages.
void read_file(const std::string& path) {
std::ifstream in(path); // file stream to read file
std::unordered_map<std::string, std::vector<double>> map;
/*
* map structure to hold data, you do not have to use this.
* I am using it only for demonstration purposes.
* map takes string (name) as KEY and vector<double> as VALUE
* so given a NAME you can get the corresponding grades VECTOR
* i.e.: map["Johnson"] --> [85, 83, 77, 91, 76]
*/
std::string line;
while (std::getline(in, line)) { // read entire line
if (line == "") continue; // ignore empty lines
int last_alpha_idx = 0; // name ends when last alphabetic is encountered
for (size_t i = 0; i < line.size(); i++)
if (std::isalpha(line[i])) last_alpha_idx = i; // get index of last alpha
std::string name = line.substr(0, last_alpha_idx + 1); // name is from index 0 to last_alpha_idx inclusive (hence +1)
std::string numbers = line.substr(last_alpha_idx + 1); // array values the rest of the line after the name
std::stringstream ss(numbers); // this is an easy way to convert whitespace delimated string to array of numbers
double value;
while (ss >> value) // each iteration stops after whitespace is encountered
map[name].push_back(value);
}
}
You could read it into an array, the code will not change dramatically. I chose string as KEY and vector<double> as VALUE to form KEY/VALUE pairs for the dictionary (map).
As you can see in the code, it looks for the last alphabetic character in each line and takes its index to extract the name from the read line. Then it takes the rest of the string (just the numbers) and puts them into a stringstream which will extract each number individually in its inner loop.
Note: the code above supports having full names (e.g. "Johnson Smith 85 83 77 91 76").
I am working on a program that is supposed to read in a file (each line in the file represents a hand of 13 cards) and evaluate each bridge hand.
I will ask my specific questions at the end, but because there is a good bit to this program I am going to include all the instructions so you get an idea of what is required.
Here is the text file that will be read in:
2C QD TC AD 6C 3D TD 3H 5H 7H AS JH KH
3C 4C 2D AC QC 7S 7C TD 9C 4D KS 8D 6C
2C 3C KC JC 4C 8C 7C QC AC 5C 9C 6C TC
5H 3S 4D KC 9S 3D 4S 8H JC TC 8S 2S 4C
2S 5D 6S 8S 9D 3C 2H TH
2H 6D %S 8S 7S 4D 3H 4S KS QH JH 5C 9S
2C QD TC AD 6C 3D TD 3C 5H 7H AS JH KD QS
2C QD TC AD 6C 3D TD 2C 5D 7H AS JH KD
2H 6D TS 8Z 7S 4D 3H 4S KS QD JH 5C 9S
With each pair representing a card (the value and the suit).
Legal values include:
2-9
T(10), A(Ace), K(King), Q(Queen), and J(Jack)
And suits:
C(Clubs), S(Spades), D(Diamonds), and H(Hearts)
Once the file is read in, each hand must be sorted first by suit and then by the rank within the suit (aces are high). When the sorting is complete, each hand must be evaluated using the following rules:
Aces = 4
Kings = 3
Queens = 2
Jacks = 1
voids (no cards in a suit) = 3
singletons (one card in a suit) = 2
doubletons (two cards in a suit) = 1
long suits (more than 5 cards in a suit) = 1 count for each card over 5 in number
After being evaluated, each hand should be displayed in the following format:
Example Input:
2C QD TC AD 6C 3D TD 3H 5H 7H AS JH KH
Example Output:
Clubs 10 6 2
Diamonds A Q 10 3
Hearts K J 7 5 3
Spades A
Points = 16
Here are a few specifics about what the program must include:
1. A data structure to hold cards in an ordered manner.
2. A function to read in the hand.
3. A function to evaluate the hand (with support functions).
4. A function to display the hand.
Here is what little code I've been able to come up with. In case it's not clear, the comments are steps I think will need to be done in order for the program to work properly. Right now all it does is open the file, and yes I will be removing the "File is Open" message, I just wanted to be sure the file was actually being open.
//#include <program3.h>
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main() {
//Create Array
//char bridgeHands[];
//Open file, if it doesn't exist, exit the program
ifstream bridgeFile;
bridgeFile.open("prog3.dat");
if(!bridgeFile) {
cerr << "Open Failure" << endl;
exit(1);
}
else {
//Read file into array
//Sort array
//Evaluate hands
//Display hands
cout << "File is open" << endl;
}
return 0;
}
I guess my specific question at the moment is this. How do I need to go about creating and loading the array? I have never worked with loading an array from input that is in pairs. Also, how does this work with the data structure?
I'm sure you can tell by now that I'm extremely new at this and am learning as I go (pretty much everything I know how to do in C++ is written in that code), so any help is greatly appreciated. Thank you for your time.
There are a lot of open questions in my mind. First and
foremost: should each hand be on a separate line, or is it just
the next 13 cards, regardless of line breaks. This changes the
way you read hands. In either case, your input file has errors
which must be detected: in the first case, the fifth and seventh
lines have an incorrect format, and in the second, the number of
cards isn't a multiple of 13, so there must be an error
somewhere.
Anyway, the proper way to approach this is to define types
(classes) for the cards and the hand, and defined a user defined
operator>> for each, with the operator>> for hands using the
one for cards. For example:
std::istream& operator>>( std::istream& source, Card& object)
{
char value;
char suit;
source >> std::ws; // skip leading whitespace.
source.get(value); // these do _not_ skip whitespace
source.get(suit);
if ( source ) { // no errors on input...
// Map the characters to the internal representation and write
// them into `object`. This operator may have to be a friend
// to do this.
//
// If one of the characters isn't legal:
// source.setstate( std::ios_base::failbit );
}
return source;
}
For the hand, if your input is line oriented, the best solution
is probably to use std::getline to read the line, then
std::istringstream to parse it. Make sure you check that
there is nothing but white space left once you've read the 13
cards. (If the input ignores line endings, then just reading 13
cards should be sufficient.) Regardless of the strategy, be
sure the check for errors after each read, before using the
values you've read. So you're loop (either on the
std::istringstream or the original source, depending) might
look something like:
int i = 0;
while ( i != 13 && source >> dest[i] ) {
++ i;
}
if ( i == 13 ) {
// Input of 13 cards succeeded...
}
Finally: You're input contains errors (probably intentionally,
to ensure that you test them correctly). Which means the
simplest form of the outer loop won't work correctly (since it
will stop at the first error). If we suppose line oriented
input globally, but the >> operator for hand ignores line
endings and just looks for the next 13 Card:
std::string line;
int lineNumber = 0;
while ( std::getline( source, line ) ) {
++ lineNumber;
std::istringstream parser( line );
if ( parser >> hand >> std::ws && parser.get() == EOF) {
// Line is good, hand contains the instance to be evaluated
} else {
std::cerr << "Input format error in line " << lineNumber << std::endl;
}
}
Concering the condition in the if: we read a hand, then skip
white space; if that succeeds, we verify that we have reached
end of file (otherwise, there's extra garbage at the end of the
line). You can give a more detailed error message if you
separate these different operations out, although to indicate
which card is in error, you'll have to input the 13 cards
directly at this level, rather than using the >> for Hand.
One other suggestion: I would choose an internal representation
which made processing simple, with mapping functions for input
and output. This is probably two enums: one for values (with
the values in the order of their ranking), one for suits (also
in the order of their ranking). This will make the sorting
and the counting significantly easier, and mapping functions are
very easy: for small sets like these, nothing more than an array
with the legal representations: on input, a linear search, and
on output, just index. (Note that this may result in the value
2 having the numeric value 0 internally, since it will be
the first value of the enum.)
Use the ifstream::getline() function for reading and parsing the file. At this link you also find a nice example how you might read the file directly into a std::array:
#include <iostream>
#include <sstream>
#include <vector>
#include <array>
int main()
{
std::istringstream input("abc|def|gh");
std::vector<std::array<char, 4>> v;
// note: the following loop terminates when std::ios_base::operator bool()
// on the stream returned from getline() returns false
for (std::array<char, 4> a; input.getline(&a[0], 4, '|'); ) {
v.push_back(a);
}
for (auto& a : v) {
std::cout << &a[0] << '\n';
}
}
But take a close look whether this is suitable for your case. As an alternative you could omit the last parameter of getline so you really get the lines one by one. Then you'd have to parse these lines using std::string::find() and std::string::substr().
I have searched anywhere I could to find such thing, believe it or not, for around 3 months...
And it also came to my mind that this is probably something incredibly easy...But after experimenting lots of times, I had no success.
It might be possible to find this somewhere else, but I'm also not sure how to search for it, that's why I'm asking here.
So here's what I want to do:
I have a file like this
[Property]
1 Din 17 M 10 D FFF
2 Dout 12 F 11 F FFF
[Names]
1 Din
2 Dout
The file ends here.
I want to read the whole file into variables, which I already do, for example:
std::ifstream readP("properties.dat");
unsigned short ID;
std::string Name;
unsigned short p2;
char p3;
unsigned short p4;
char gTemp;
std::string fProperty;
while(readP >> ID >> Name >> p2 >> p3 >> p4 >> gTemp >> fProperty);
Now I want to read everything, except the [Property] and the [Names], because obviously with these fields in the text, the reader will not read, because they aren't being read from the while loop.
What would be a good way to accomplish this?
You must do a bit more elaborate parsing.
So, try this:
Read a line.
Decide how to process it.
A) Skip.
B) Parse into variables.
You cannot "ignore" lines, but you could "skip" them.
I would suggest reading sequentially line by line with std::getline then skip the uninteresting stuff.
Notice that lines don't really exist in most file systems (at least Posix ones). Lines are just conventionally terminated by \n but a file is a sequence of bytes.
You should read line by line, and the determin whether you are going to process this line.
You can check if the first character is [ or not.
http://www.cplusplus.com/reference/string/string/at/
if (str.at(0) != '[')
{
//Process this line by splitting the string with space ect
}
this is quite a primitive problem, so I guess the solution shouldn't be hard, but I didn't find a way how to do it simply, neither have I summarized it to actually find it in the internet.So going to the question, I have a file of information like this:
1988 Godfather 3 33 42
1991 Dance with Wolves 3 35 43
1992 Silence of the lambs 3 33 44
And I have a requirement to put all the information in a data structure, so lets say it will be int year, string name and three more int types for numbers. But how do I know if the next thing I read is a number or not? I never know how long is the word.Thank you in advance for anyone who took their time with such a primitive problem. :)
EDIT: Don't consider movies with numbers in their title.
You're going to have some major issues when you go to try to parse other movies, like, Free Willy 2.
You might try instead to treat it as a std::stringstream and rely on the last three chunks being the data you're looking for rather than generalizing with a Regular Expression.
your best bet would be to use C++ regex
That would give you a more fine grained control over what you want to parse.
examples:
year -> \d{4}
word -> \w+
number->\d+
If you do not have control over the file format, you may want to do something along these lines (pseudo-process):
1) read in the line from the file
2) reverse the order of the "words" in the file
3) read in the 3 ints first
4) read in the rest of the stream as a string
4) reverse the "words" in the new string
5) read in the year
6) the remainder will be the movie title
Read every field as a string and then convert the appropriate string to integers.
1)initially
1983
GodFather
3
33
45
are all strings and stored in a vector of strings (vector<string>).
2)Then 1983(1st string is converted to integer using atoi) and last three strings are also converted to integers. Rest of the strings constitute the movie_name
Following code has been written under the assumption that input file has already been validated for the format.
// open the input file for reading
ifstream ifile(argv[1]);
string input_str;
//Read each line
while(getline(ifile,input_str)) {
stringstream sstr(input_str);
vector<string> strs;
string str;
while(sstr>>str)
strs.push_back(str);
//use the vector of strings to initialize the variables
// year, movie name and last three integers
unsigned int num_of_strs = strs.size();
//first string is year
int year = atoi(strs[0].c_str());
//last three strings are numbers
int one_num = atoi(strs[num_of_strs-3].c_str());
int two_num = atoi(strs[num_of_strs-2].c_str());
int three_num = atoi(strs[num_of_strs-1].c_str());
//rest correspond to movie name
string movie_name("");
//append the strings to form the movie_name
for(unsigned int i=1;i<num_of_strs-4;i++)
movie_name+=(strs[i]+string(" "));
movie_name+=strs[i];
IMHO Changing delimiters in the file from space to some other character like , or ; or : , will simplify the parsing significantly.
For example , if later on the data specifications change and instead of only last three , either last three or last four can be integers then the code above will need major refactoring.
If I open a new file for input, and I call input >> listSize; outside of a while loop and then continue calling input >> anothervariable will it automatically progress through the file or will it read the first line again?
Example:
input >> listSize;
BaseStudent* studentlist = new BaseStudent[listSize.atoi()];
while (!input.eof())
{
input >> anothervariable; // I want this to start on the second line, not the first
}
The input file looks like this and we can code to the pattern (ignore the extra blank lines):
12
Bunny, Bugs
Math 90 86 80 95 100 99 96 93
Schmuckatelli, Joe
History 88 75 90
Dipwart, Marvin
English 95 76 72 88
Crack Corn, Jimmy
Math 44 58 23 76 50 59 77 68
Kirk, James T.
English 40 100 68 88
Lewinsky, Monica
History 60 72 78
Nixon, Richard
English 35 99 70 70
Lincoln, Abraham
History 59 71 75
Clinton, William
Math 43 55 25 76 50 58 65
Duck, Donald
English 34 100 65 65
Duck, Daffy
History 55 70 70
Bush, George
Math 44 54 29 75 50 55 60
When you read from a stream the data is used.
Next time will read from the last point read "up-to"
Though stream operator >> will skip proceeding white space but will not read the white space after the object (which can be a pain if your input is line orientated, as you don't see new lines easily).
The best way to get around this is to explicitly read lines at a time then parse the line:
std::string line;
std::getline(input, line); // Read a line
// Now look what is in the line.
std::stringstream linestream(line);
linestream >> dataItem1 >> dataItem2 >> dataItem3; /// etc.
Also note:
// This is not good. If there are any errors in your file it will loop forever.
while (!input.eof())
It is normal to loop over the input using:
while(input >> data)
{
// If you get in here then the read worked.
}
// You will fall out of the loop when
// 1) EOF
// 2) There is an error.
So if we combine both techniques:
std::string line1; // Name,
std::string line2; // Scores
std::string empty; // Empty line in data file.
while(std::getline(input, line1) && std::getline(line, empty) && std::getline(input, line2))
{
// line1 => Bunny, Bugs
// empty =>
// line2 => Math 90 86 80 95 100 99 96 93
// Enter the loop only if we get a name and a score line
std::getline(line, empty); // Optionally read a trailing line (there may not be a last one);
// dataStream => Math 90 86 80 95 100 99 96 93
std::stringstream dataStream(line2);
std::string subject;
int score;
dataStream >> subject; // subject => Math
while(dataStream >> score)
{
// We read another score from the data line;
// score is 90 first time 86 second time etc.
}
}
Others have already pointed out that the answer to your question is "yes", so I won't worry about that part.
As for the rest, I think I'd write it a bit differently. Your file obviously represents structured data, and I'd write the code to reflect that fact reasonably directly. I'd start by defining a structure reflecting the data in the file:
struct test_scores { // maybe not tests. Change if appropriate
std::string student;
std::string course;
std::vector<int>
};
Then, I'd write a function to read one of those items from the file:
std::istream &operator>>(std::istream &is, test_scores &ts) {
// for the moment assuming there are no blank lines in the file.
std::getline(is, ts.student);
std::string temp;
std::istringstream buffer(temp);
buffer >> ts.course;
int score;
while (buffer>>score)
ts.scores.push_back(score);
return is;
}
In C++, however, it's really easier to just read whatever amount of data is there, than to prefix the data with the count. Given that count is present, the easiest thing to do is probably to just read and ignore it:
std::string ignore;
std::getline(infile, ignore);
Then we can read the real data pretty easily:
std::vector<test_scores> student_scores;
test_scores tmp;
while (infile >> tmp)
student_scores.push_back(tmp);
...or, we can use C++'s handy-dandy istream_iterators to simplify the code even more:
std::vector<test_scores> student_scores((std::istream_iterator<test_scores>(infile)),
std::istream_iterator<test_scores>());
That's it -- it defines the vector and initializes it from the input file, all in one (fairly) simple operation.
Thew file pointer is always advanced past what you have already read.