C++ :: String Operation While Reading Line By Line From A File
May 12, 2014
I have to read the information about logic gates from a file. The file format is shown below:
Code:
gateOne = NAND(inpA, inpB)
gate2=NAND(1,2)
3 = NAND(23,25,26)
As, it can be seen from the above structure that whitespaces are not same everytime. So, to deal with this situation, i am using boost library to remove all whitespaces from the line which is being read and then try to find the name of gate and its input. My code is given below which is able to correctly find the gate names and its first input...but my code is not able to find the second, third and so on input names.
Code:
//C
#include <stdio.h>
//C++
#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <cstring>
#include <boost/algorithm/string/erase.hpp>
[Code] ....
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Aug 17, 2014
I am trying to read a file line by line and then do something with the informations, so my method looks like this:
Code:
void open_file(char *link) {
FILE *file = fopen(link, "r");
if (file == NULL) {
fprintf(stderr, "Could not open file.
");
exit(EXIT_FAILURE);
[Code] ....
1) The first complain of valgrind is at the line where I use fgets and its telling me (invalid write of size x), but I have allocated my line to 56000 and the read line is shorter, why is there a write size error then :S?
2) at the line where I realloc where I try to shrink the space he's telling me: Address .... is 0 bytes inside a block of size 56000, But I know i need only this space so why is there a write over space error :S??
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Sep 25, 2013
So I'm reading a file line by line and storing it backwards into a list. So if the file has has this format...
1
2
3
4
The code should store each line in a list as such...
4, 3, 2 ,1
Instead the code will store the last variable in all nodes. So the final list will look like this...
4, 4, 4, 4
Here is my code...
struct node *head = NULL;
int i;
while(read(in, &i, sizeof(int)) != 0) {
struct node *temp = malloc(sizeof(*temp));
temp->line = &i;
temp->next = head;
head = temp;
}
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Apr 12, 2015
Im trying to read from a file, line by line, with no specified number of values in the file. Check out my code:
int main() {
string x;
ifstream fin;
int count = 0;
char ch;
fin.open("CWC_Master.txt");
if(!fin)
[Code] .....
Now, this works great! However, its skipping some lines. And I dont know why. For example: Lets say that the input file is:
superman toy
sm2335
19.99
batman toy
bm5532
25.99
aquaman toy
am6786
26.00
Where it should output the above, instead it outputs every other one. Like:
superman toy
19.99
batman toy
25.99
aquaman toy
26.00
How can I fix my code so that it SIMPLY(i say simply because I am still a beginner coder) can read line by line?
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Oct 13, 2014
How to read a file line by line and then later access them by doing something like
Code:
lines[0] //Line number one
...
lines[100] //Line number one hundred and one
lines[100][0] //L
lines[100][1] //i
lines[100][2] //n
lines[100][3] //e
lines[100][4] //
lines[100][5] //n
...
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Jul 5, 2013
I have a text file (test.txt) with the following data:
01,05,25,20130728
01,06,25,20130728
01,07,25,20130728
01,08,25,20130728
01,05,25,20130728
01,05,25,20130728
01,05,45,20130728
01,05,65,20130728
01,05,85,20130728
01,05,35,20130728
01,05,25,20130728
01,05,35,20130728
I want to read this to one string called line. So far I have this code:
string line;
ifstream myfile ("/home/Test.txt");
if (myfile.is_open()) {
while (myfile.good()) {
getline (myfile, line);
for (int a = 0; a <= 335; a++) {
cout <<line.at(a);
} }
myfile.close();
}
so far its only printing the first line and then throwing an instance of 'std::out_of_range'
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Jul 27, 2013
First of all I need to know how to read from file.
Second, I need to read line by line from the file.
For example, the file contains:
8H 3S TH 9D 5S
5D KD 9H 4D 3D
8C TD 5D QS 2C
I wanna use array, so I need to store 8H in array[0], 3S in array[1], until 5S get stored in array[4].
I need to read the first line, the the second, and then the third.
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Mar 7, 2014
How can a mulitline string be read line by line
ex: str = "PERIOD="week"
DAY="day"
TIME="time"";
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Sep 11, 2014
void login() {
//username, password, option to register, option to exit, link to website
cout << "Would you like to login(1), or press anything else to register.?" << endl;
cin >> loginYorN;
if (loginYorN == 1) {
cout << "Please enter your username: ";
cin >> accountInfo[1];
[code]...
So as above, I ask them to input 1 for login, anything else for register. Whatever they input, it get's stored into loginYorN, then I check to see what they input. If they put '1' for input, then I ask them for their username, store that into accountInfo[1], and then asking for the password, storing that into accountInfo[2].
Now here is where I need to input line 1(username) from login.csv or login.txt and line2(password) and storage these into accountID and accountPW.
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Mar 6, 2015
how to read the next line in the file. I think I need to use a for loop, but not sure how to implement it.Lets say my input.txt file has three names:
Sally
Tom
Sugar
I can get Sally, but not tom as yet. fgets also gets me to the same place.
Code:
int main(){
char str_1;
FILE * ifp = fopen("input.txt", "r");
fscanf(ifp, "%s", &str_1);
printf("%s", &str_1);
return 0;
}
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Jul 15, 2013
I need to read lines from one file and copy them line by line into another file using dynamic memory allocation. It compiles but gives me a seg fault. Why/How?
Code:
int main(){
FILE *fp1;
FILE *fp2;
FILE *i;
fp1=fopen("file1","r");
fp2=fopen("file3","w+");
[Code] ....
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Nov 15, 2013
My file has these lines.I try to remove extra line in the end, in notepad/gedit, however, after saving it automatically adds up there.
one
two
three
Code:
void help::read_ref(const char* file_name){
std::ifstream file_handle;
file_handle.open(file_name);
std::string line,name;
getline(file_handle,line);
while(!file_handle.eof()){
[code]......
when I print size of map, it comes out to be an extra then what is should be.
std::map<std::String,std::string> ->is my map
on the contrary if I use Code: file_handle >> line; I get correct number of entries in map.
My doubt: getline, automatically finds and in last, it finds a , why it doesn't end the iteration?
I have faced this issue many number of times.
Code: line[0]=='>' I am making this check, then also, I get a null string as key in my map.
I have printed key with their index, using Code: map iterator .
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Jul 11, 2013
I'm currently working on making a program that is run through a GUI run through the command line. The program basically takes an app file and a boot file and runs it through a bunch of functions and generates a new outfile. Anyway I'm new to C and can't figure out how to code it so I can type the two file paths into the command line and read them into the function. Is it possible to do this within the "if else" statement?
Code:
int main(int argc, char *argv[]){
const char * const SrcFilePath;
const char * const SRecordPath;
const char * const FopIspFilePath;
[Code] ....
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Mar 6, 2014
finding the last line of the code? I have a program with two functions that open and display a joke.txt and punchline.txt file. My joke function (which reads the entire file) works fine. The punchline function, however, does not.
void displayPunch(fstream &file)
{
char ch;
string fileLine;
bool isLine = true;
file.seekg(0L, ios::end);
while(isLine)
{
file.seekg(-1L, ios::cur);
[code]....
The file, punchline.txt, has a bunch of garbage strings with one real string at the end. I need extract and display only the final line of that file.
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Oct 5, 2013
I need to read a text file which has various lines containing integers. I need to write those integers separately in a vector. Example, the first line of the text file contains 3 9 8 7 6 so vector[4]=3, vector[3]=9, vector[2]=8 and so on. Next read the second line 4 1 2 3 4 5 and write to another vector vector[5]=4, vector[4]=1...
I tried the code below but it will write from the second line, the whole line in one vector index.
int str; // Temp string to
cout << "Read from a file!" << endl;
ifstream fin("functions.txt"); // Open it up!
string line;
// read line count from file; assuming it's the first line
getline( fin, line );
[Code]...
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Aug 24, 2013
I can able to get the last line ten chars but i cant get if the last line is null.
here is my code
#include <cstdlib>
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
using namespace std;
int main(int argc, char *argv[]) {
[Code] ....
here with i have enclosed my file where i am pick my last ten chars ...
Attached Files : log.txt (4.8 KB)
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Oct 19, 2013
I know how to do it in C, but in C++?
Here is my code. Let the variables be of type double.
Code:
while(infile) // Will read the last line twice
{
if(!N)//Read first line of file
{
infile >> d;
infile >> N;
infile >> epsilon;
infile >> t;
[Code] .....
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Feb 7, 2014
i would like to read the content of a text file data.txt (line by line ) directly from the command line using this command: a.exe < data.txt.
What could be the c++ code to read/get the content of these lines (without using ifstream). The treatment of the lines is not a problem for me but i really don't know how to access the content of the file from the c++ code
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Dec 23, 2013
My question is how can i read one line from a ".txt" file? To be more clear, i'm trying to write a hangman game. Therefore I'm trying to get words from a "wordlist.txt" file i created. I know a little bit about ifstream, ofstream and fstream. So my function i created to get a random line from this txt (not-completed yet since i don't know how to get that randomized line);
void grw() {
int line;
srand (time(NULL));
line = (rand() % 7972) + 1;
ifstream wordlist;
wordlist.open("wordlist.txt");
}
I created a variable called 'line' for the line number and randomized it (there are 7972 words in ".txt" file). So what i want to do now is to get the word on that line.
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Feb 23, 2014
I have attached the file that I need to read into a data structure. In the example I am just printing it to the screen. This following code has worked for me before, but now isn't. I have tried in visual studios, and on unix, and neither are running it. I ultimately need it to run on unix.
Example file:
word
book
programming
Here is my function to read in the file.
ifstream file;
string line;
file.open("words.txt");
if(file.is_open()){
while(!file.eof()){
getline(file, line);
cout << line <<endl;
}
}
file.close();
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Feb 9, 2012
Why this code outputs 7 lines (the last line twice) while the file contains 6 lines?
cout << "read msgfile
";
ifstream msgfile ("script1.msg");
while (msgfile.good()) //if not at end of file, continue reading {
// load vector with deffile
msgfile >> line;
vectormsgfile.push_back (line);
cout << line << "
";
}
msgfile.close();
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May 2, 2013
I'm trying to read a file from the 2nd argument, skipping the first line of the file since it's the name of the columns, and separate each line as a token, by date, subject, startTime, endTime, and location.Here's my code that I got so far:
Code:
void readAppointment(){
if (arg != 2)
exit;
else {
FILE *fp;
fp = fopen( argv[1], "r");
char line[999];
[code]....
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Mar 27, 2013
I am working on a project for school that has us read in a text file that contains 8 lines of SSN and grades. I am not sure how to go about reading in the lines and differentiate between the SSN and grades in the calculations.
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Nov 9, 2013
I tried to read in a file that contain studentId(8 integer long) and GPA in the same line separated by a comma, but I couldn't. Example:
145453565, 4.0
34344443, 3.9
23454345, 3.4
12345678, 3.4
void studentRecord::loading(string filename) {
ifstream infile;
int studentId;
double GPA;
[Code] ....
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Jul 2, 2013
I have an external file with one column of data. If I have a counter value let say counter =1, and counter++ and so on. How I can write such a c++ code that if the value of counter and value from the external file are same then generate an action let say cout both values i.e. value of counter and value from external file.
for more information, here is an example:
data in file(in one column): 2 6 8 9 10...
value of counter : 1 2 3 4 5 6 7 8 9...
then cout values only if value of counter and value from the file is same.
Here is my code so far, but it does not seem to work;
#include<iostream>
#include<fstream>
using namespace std;
int main() {
const int SIZE = 10; //Size declaration of array
int hours[SIZE]; //Array declaration
[Code]...
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Jan 23, 2015
I am reading my file (20GB) line by line using boost like this
PHP Code:
boost::interprocess::file_mapping* fm = new boost::interprocess::file_mapping("E:Mountain.7z", boost::interprocess::read_only);
boost::interprocess::mapped_region* mr = new boost::interprocess::mapped_region(*fm, boost::interprocess::read_only);
char* bytes = static_cast<char*>(mr->get_address());
An exception is thrown in the second line while allocating memory for mr.
I use boost because it can also work in Mac which my code will be ported to.
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