C++ :: Reading File Values By Passing Reference To A Function?
Oct 11, 2013
I am trying to read the file which has the values stored in the following pattern
2 4 10 103 2 504 .... and so on
I Have opened the file and then passed the opened file to another function to process it further.
here is my code
#include <iostream>
#include <fstream>
#include <vector>
#include <stdlib.h>
[Code].....
now the problem is when the control exits the "while loop" in the function "readingValues(std::ifstream& myFile)it goes straight to catch block ?
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Mar 4, 2013
If f1 and f2 are two user defined functions.
main(){
int *p;
f1(&p)
}
f1(**p){
f2(&p);//
If I've to pass the pointer by reference again in another function, will I've to do something like this?
}
f2(***p){
**p = NULL;
}
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Sep 25, 2012
I created the following code to pass the the variable 'inputVoltage' by reference to the function 'input'. It certainly works when I run the program, but I dont think it is a standard way of doing it, i.e. the use of '*' and '&' is not according to convention ? Or perhaps the way did it is acceptable ?
int input (double *inputVoltage);
int main ( {
double inputVoltage;
input(&inputVoltage);
[Code]....
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Mar 16, 2013
I am working on incorporating a function in to an already existing piece of code, I have incorporated the function fine as far as I am aware.
The problem I have is that I am trying to pass two int arrays to the function, so that i can manipulate and compare them "the values will be changed the originals cannot be changed"
I am having trouble pulling the information out of the already created array, I am able to pass the pointer reference for the single value which is not exactly what i want "best_prog".
My function is below I have commented the memcpy parts and also the majority of the code isn't there cause it is not needed to see make the copy work.
int edit_distance(int index) {
struct prog *progp = &population[best_prog];
/* The struct of best prog not sure if i need one for the other prog I am trying to compare it with the one below doesn't work as intended.*/
//struct prog *progp = &population[];
int editdistance = 0, ar1 = 0, ar2 = 0, a = 0, b = 0, j = 0, x = 0;
[code].....
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Sep 19, 2014
Basically I'm trying to pass an object as a reference to the template function, rather than a copy as it's seeing. I'm needing to do this without editing Obj::Call to accommodate a reference as its first parameter, as it'd break other calls.
You'll notice in the following code the object will be destroyed upon passing, while the object defined is still in-scope due to the infinite end loop.
#include <iostream>
#include <string>
using namespace std;
class Obj {
public:
string name;
Obj(string name): name(name) {cout << "create " << this << endl;}
[code]....
In the past I tried ref(), which appeared to stop this happening, however it created a blank copy of the object instead.
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Jul 6, 2013
The program asks for to ask the user for how many students there are, and how many strawberries they picked. The farm gets to keep half and the students get to keep the rest.
I am using functions and passing values to one function to another. I know I am making it harder then I need to, but I want to work with functions more and passing values. I figured it was better to practice with simple programs.
Code: #include <stdio.h>
float people(float);
float strawberries(float x);
[Code].....
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Apr 29, 2014
I'm working through the Let us C book. One exercise asks me to collect int and float , then pass them to a function that gets product of these and returns it to main. My code looks like this:
Code:
#include <stdio.h>#include <stdlib.h>
main()
{
int a;
float b, c;
[Code]...
So while compiling i get an error about conflicting types for product. I tried to google that error but couldn't understand what's the problem. My only clue is that i can't pass int and float to a function at the same time... Could that be it?
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Jan 28, 2014
#include "stdafx.h"
#include <iostream>
#include <math.h>
#include <time.h>
#include<iomanip>
#include<array>
#include <algorithm>
using namespace std;
const int AS = 6;
void FillingRandomly(int (*)[AS]);
void printing(int (*)[AS]);
[Code] ....
Basically I have to create an array, fill it, and then print it on screen. The tricky thing is that need to use pointers to fill it and print and later on sort it. My problem is that with this code is that i get
Error2error C2109: subscript requires array or pointer typec:userspcdesktopusbanthonydocumentsvisual studio 2012projectsessaieessaieessaie.cpp55
and
5IntelliSense: expression must have pointer-to-object typec:UserspcDesktopUSBAnthonyDocumentsVisual Studio 2012ProjectsEssaieEssaieEssaie.cpp55
Whenever I try to run it.
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May 9, 2014
This read a file (arrival time , brust time) for n processes and suppose to do shortest job first scheduling. the file read correctly but passing the value to SJF function gives read of 0's to all values .
#include<stdio.h>
#include<stdlib.h>
typedef struct {
int brust_time[10];
int arrival_time[10];
}Time;
[Code] .....
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Feb 3, 2015
I have the main() - which has entries like
Code:
main() {
int ss, ret, z;
float yy;
ret = function1(&yy, &ss, &z);
//int function1(flat *cc, int *dd, int *k) - is it correct?
[Code]...
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Sep 26, 2014
typedef struct example_dt_struct {
int a;
float b;
char* c;
};
typedef void(*func)(example_dt_struct *s, int e, int f);
void f(func *n){}
how can i use example_dt_structure with my function pointer into f()
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May 24, 2013
I'm trying to passing values from a text file to an array. The values in txt file is;
0 2 3 5
1 2 5
0 1 3 6
1 3 5
I need to store these values in an array like that
Code:
int array[?][?]={{0,2,3,5},{1,2,5},{0,1,3,6},{1,3,5}};
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Jul 5, 2014
I'm trying to pass these numbers into the array using the for loop: 1, 2, 3, 4, 5. I created two files in my project called "inStuff.txt" and "OUTPUTS.txt". I know I have an error at my input in the for loop, which is a bit similar to my problem or something? I'm also on linux using a crossGCC complier(not sure if that makes a difference).
#include <iostream>
#include <fstream>
using namespace std;
[Code]....
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Jan 21, 2014
My problem is that I need to take a csv or excel file with tens of thousands of datapoints, write all points in a section of column to an array, perform calculations on them, and then write it back into another column.
I've been looking all over the internet for ways to do this easily. So far I have not found anything that I can follow and implement.Some codes have been slightly useful, but they aren't commented in a way I can understand. How to write code to take, for instance, lines from column b between 500-1000, write them to an array, and write another array 500 characters in column c. If that code could be commented, I have tried a few different techniques (counting commas), but haven't gotten anything to work.
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Oct 5, 2013
I have a .txt with a 0 or 1 to each line of the txt file. there are many values to read. I am reading the values and calculating how many each reoccur in a sequence (run-length encode). If i only use say 50 values coming in it works, but once i do the hundreds there are in the file it hangs. i am not sure why.
Code:
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
FILE *infile;
FILE *outfile;
void PrintBinary(int x,int y);
[Code] ....
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May 20, 2013
We are supposed to split this lab into 3 files a .h and 2 .cpp's. The code I'll be talking about is going to be directed at the main.cpp file. Basically we are supposed to be able to enter as many classes into the program and when you are done the program is supposed to save the contents into a .dat file. This lab is working off of an older lab so I already have a .dat file I am trying to test with this program by reading it into my program when I first run it I prompt if the user wants to load previously entered courses and if they reply with a 'Y' the program will load the contents of the .dat file. Problem is right now when I load from the .dat file only the first class is correct. Every other class after that is just giberish. I've tried everything but can't get the restore part working. I also cannot get the save to .dat portion of this lab working either.Here is my code:
#include "Course.h"
#include <iostream>
using std::cout;
using std::cin;
using std::endl;
using std::ios;
[code]....
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Mar 25, 2013
I am trying to read an array values from Tmin.txt file. I take array size from user viz. number of raw & column and then, read the following data from Tmin.txt file which look like this:
20 40 20 25 30
20 30 40 20 25
20 40 20 25 30
20 30 40 20 25
30 40 40 30 40
I am using getline, and then converting it to int by using atoi. But my code is not working.
Code :
// reading a text file
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
[Code] ....
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Apr 12, 2014
My game is a sort of RPG with stats, money etc. I just recently added a save/load system using writing to a file. I initially got writing to a text file to work, then I got loading to work too.I eventually was able to read numbers from the file and assign them to integer variables in order.
My issue was I wanted to check if a save file existed, if it did, load it up, if it did not, go to character creation. I had a lot of trouble with this and after trying different code snippets to work I finally got it to check if a file existed, and execute the appropriate code.
My issue now is my code USED to go through each entry and assign variables in order.
Like the first number in the text file would be for the variable money, and it would read it, assign to to int money and scroll to down to the next variable for player strength, assign to to playerstr variable and so on. After making the tweak for loading it no longer functions like this, and makes the last entry in the text file the value for everything.
Here's my code:
Save Code:
{
ofstream savegame;
savegame.open("C:/Sounds/savegame.dat", ios::trunc);
savegame << money << endl;
savegame << playerstr <<endl;
[Code]....
I barely get how this code works, how can I tweak it to go through the file in order and assign variables one at a time?
At the current moment, it assigned the playerstr value to both money and playerstr int. But the save file being created lists the correct values in order.
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Dec 1, 2013
I am trying to read hex data from a file (not just hex values in text format). I was able to read it (02 EC) with "fread" into an char before but I need to change the Hex value into an integer in decimal.
I already read about strtol but I would prefer reading the hex Value into an integer.
Here is my code so far:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main() {
int itrack1[1];
int itrack2[1];
[Code] ....
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Dec 26, 2012
I have problem reading CSV file, i found many solutions but i still got one problem. I need to read CSV file and then these values show in List Control and here i have problem. Idk how to display it in List?
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Apr 4, 2014
I am attempting to read values from a file into a 2d array temp[31][2] (31 rows, 3 columns).I only want the values from the file to be read into the first two columns.I believe I am accomplishing that but when I go to print the array, I expect the first two columns to have the file data and the third column to have all zeros. The third column, however is printing such that the value is the next row/first column.
I'm not sure for instance why on the bottom loop for line 1 it doesn't print:
temp[0][0] temp[0][1] temp[0][2] 20 49 0 It instead prints: 20 49 1
Code:
#include <stdio.h> Code: #include <math.h>
FILE *inptr;
int main() {
int temp[31][2] = {0}, tempavg[31][2] = {0};
int i, j, k, sum;
inptr = fopen("ProgrammingProject14.txt", "r");
[code]....
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May 6, 2013
So I have this text file that I am trying to read from and store the values of each line in multiple variables.
Let's say my text file contains
AXSYZ3482 Tom 100 112
and my code below here works fine when the lines in the text file is separated by spaces.
while (fscanf(fp, "%s %s %d %d
", userID, name, &startLoc, &endLoc) != EOF) {
printf("%s %s %d %d
", userID, name, startLoc, endLoc);
}
But let's say my file was to look like this instead.
AXSYZ3482:Tom:100:112
But if i try this below...
while (fscanf(fp, "%s:%s:%d:%d
", userID, name, &startLoc, &endLoc) != EOF) {
printf("%s %s %d %d
", userID, name, startLoc, endLoc);
}
It seem to store the entire line in userID including the ":". I want to ignore the ":"'s and store everything in between in respective varibles in the order specified above.
So first string in userID, then ignore the :, then second string in name, and ignore the next :, and so forth. How I can accomplish this?
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Dec 19, 2013
I have in my main(), a function that creates my arg object using boost/program_options.hpp i want to pass this object to another function using templates like this:
Code:
template <typename Targ>
void Count(Targ & arg){
MyObj<string> QueryTab(arg["input-file"].as<string>()); //line number is 352
...
}
However I get an error:
Code:
../include/Filter.hpp: In member function ‘void Count(Targ&)’:
../include/Filter.hpp:352:40: error: expected primary-expression before ‘>’ token
../include/Filter.hpp:352:42: error: expected primary-expression before ‘)’ token
... obviously it does not recognize my intention, what did I do wrong?
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Aug 26, 2014
Why wouldn't this code compile when adding '<double>' after the function call?
template<class T>
T add(T& a, T& b){
return a + b;
}
int main() {
int a, b;
cin >> a >> b;
cout << add<double>(a,b);
}
Compiler error:
cannot convert 'a' (type 'int') to type 'double&'
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Mar 1, 2013
I make a class (it stands for an ARMA time series), and I have a method wich modifies some of its variables. In other part of my program I have a function wich receives one object of this class as a parameter and, at some point, it calls the method of the ARMA class to modify it; here is my deal I want to pass the ARMA class by reference to this function, because I want the variables of the instance I'm passing to be modified, not those of a copy the method uses. Also, I would like not to declare the function inside the class ARMA, cause I use it in other places too (it's basically a Nelder-Mead optimization what it performs).
Here is a code wich sketches what I've been trying, and exactly the error message I get is "modifyParameter has not been declared".
#include <iostream>
#include <cstdlib>
using namespace std;
class ARMA{
[code]....
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Dec 31, 2012
How can I pass a matrix as a reference parameter? I am using the following declarations:
Code:
typedef std::vector< std::vector<std::string> > ss_matrix_t;
I declare the matrix with the following statement, where nRows and nCols are integers
Code:
std::vector< std::vector<std::string> > vI2Matrix(nRows, std::vector<std::string>(nCols,""));
The function is called with:
Code:
int read_files(std::string fname, int nCols, int nRows, ss_matrix_t &ssMat )
But I get a linker error:
error LNK2019: unresolved external symbol "int __cdecl read_splayed_files(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,int,int,class std::vector<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::allocator<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > >,class std::vector<class std::vector<class
[Code] ....
I suspect the syntax of the declaration, but I am not sure what to do here? If I change the call to the function, then the array ( matrix ) is passed by value, and it takes forever:
Code:
int read_files(std::string fname, int nCols, int nRows, ss_matrix_t ssMat )
// this takes ages ( it does compile and link )
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