C :: Losing Contents Of A String Between File I/O Operations
Oct 24, 2013
Here's the code I'm writing:
Code:
#include <stdio.h>
#include <stdlib.h>
char* getTeamCode(char* team);
[Code]....
Why the placement of the code on line 21 above matters.
It grabs the correct string just fine. If I write a printf just below it, it prints the string it should correctly. However, if I do a printf of the string OSUteamCode below the fopen call on line 23, it prints blank.
So the first thing I did was move it below the fopen line. It worked, finding and outputting the first game in "game.csv" just fine, but not the other 11. Debugging with printf shows that the contents of OSUteamCode again disappear after the fopen call in the addLineCSV function.
I'm not understanding why that happens. The only thing I can figure is there's something going on with the file I/O commands that I just don't understand, but I can't find anything online that explains what that might be.
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Oct 1, 2014
I am trying to code a function which will read a file on system and return its content back as string. Code is below.
Code:
char * readtxt(){
FILE * fptr;
char c;
static char txt[30];
[Code]....
I suppose txt variable is pointer. But I need to return the file content as string so the function structure should look like
Code:
returnType function(){
return "File Contents as String";
}
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Oct 1, 2014
I am trying to code a function which will read a file on system and return its content back as string. Code is below.
char * readtxt(){
FILE * fptr;
char c;
static char txt[30];
int len=0;
fptr = fopen("C:UsersTestDesktopDev est.txt", "r");
[Code] ....
I suppose txt variable is pointer. But I need to return the file content as string so the function structure should look like
returnType function(){
return "File Contents as String";
}
How can I achieve this ?
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Apr 9, 2014
I'm making a program in which it will read an input from a text file and then count the numbers of spaces , characters , words . Here is what i think it would work : First i will transfer the contents from the input.txt into a string , after that i will create 3 strings which contain each of these : spaces , characters , words . Then comparing each of the contents of the intput.txt_string to the other 3 strings .
#include<iostream>
#include<fstream>
#include<string.h>
using namespace std;
[code]....
and of course it doesnt seem to work...
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Jul 18, 2013
I am working on a project that uses a web service to extract a PNG image from a web server and save it on a local machine. It's done via a system call. I can get the output of the system call to a FILE but it appears to be losing data, most notably the PNG chunk names (IHDR/PLTE/IDAT/IEND, notably). (Unfortunately piping the output to an exterior file does not work through a system call.) The end result is ~6KB smaller than the file I am intending to retrieve.
This is the code I'm using (adapted from other material I found via searches here):
ofstream png;
png.open(/*outputfile*/, ios::binary);
FILE* fp = _popen(/*SYSTEMCALL*/, "rb");
string responseString;
if(fp != NULL) {
char a[100];
while(!feof(fp)) {
fgets(a, 100, fp);
responseString += a;
}
}
_pclose(fp);
png << responseString;
Am I missing something or just doing it wrong?
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Jul 28, 2014
I keep getting this error when trying to compile.
error C2440: 'initializing' : cannot convert from 'void' to 'std::basic_ifstream<_Elem,_Traits>'
1> with
1> [
1> _Elem=char,
1> _Traits=std::char_traits<char>
1> ]
1> Expressions of type void cannot be converted to other types
Here is my entire program:
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
[code].....
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Jun 6, 2013
I need to make a program which can play a audio file as background while executing other operations .
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Jan 27, 2014
For the last part of this problem, if player 2 loses the game of hangman, I need to display the letters they did get right. In order to do that, I believe that I need to traverse vector v for the elements that exist in the string hiddenword, and then print those characters that match.
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
int letterFill (char, string, string&);
[Code] ....
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Oct 28, 2014
I am trying to write my files to another subfolder . Below is my program.
Code:
cat th6.c
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#define SIZE 8
#define NUMELM 8
[Code] ....
I observe my filename along with directory as text in the new file created in sublfolder. This is output.
[cporgs/apue/threads]: mkdir first
[cporgs/apue/threads]: ./a.out test.txt first
test.txt -- first/test.txt
dfdfdfdfdfdfdf-14
dfdfdfdfdfdfdf-14
in thread test.txt first
[cporgs/apue/threads]: cat first/test.txt
dfdfdfdfdfdfdffirst/test.txt
[cporgs/apue/threads]: cat test.txt
dfdfdfdfdfdfdf
I could not able to get from where this filename and folder is getting added.
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Jun 23, 2014
I am creating a website in which a user can upload an image to a sql database. It is converted to varbinary and then read into an Image object using a http handler to convert it to an image. this all works fine. When I open an popup window I am reading data from specific rows into textboxes, thus when the user confirms any changes the rest of the data stays the same. How can I hold the Image and redisplay it when returning to the main page after closing the pop up. It currently sets the image in the database to null as the file upload object has not been given a directory location all the time. This is my attempt at reading the image from the database and then reapplying it if the file upload is empty
private void ChangeFilm(int id)
{
SqlConnection con = new SqlConnection(my settings go here);
con.Open();
[Code].....
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May 16, 2013
I'm tinkering with a serial quick sort algorithm. Normally I use qsort() but I wanted to test this.
Somehow I loose the highest number. I can't see where I drop it.
Code:
// function to quicksort, leave them in front of qsort.
void swap(float_t *left, float_t *right){
float_t temp;
temp = *left;
*left = *right;
*right = temp;
[Code] .....
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Feb 12, 2013
I'm writing a program that stores records into a file and then these records can be printed out. A last name, first name, and score is stored to be exactly 36 characters long (using leading spaces to pad) making it easier to retrieve specific records. For example, three records stored in the file would like like this: (the underscores are simply to illustrate the distance, they are not in the file itself)
_______lastname_______firstname__90__________lname __________fname_100___________last___________first __60
When printed out, the names are formatted as follows:
lastname, firstname: 90
lname, fname: 100
last, first: 60
However, when I print them out this is what I get:
lastname, firstname: 90
lname, fname: 100$
last, first: 60H
For some reason, for any record after the first, an extra character is added to the end. These characters are not in the file, so I was thinking that the array for some reason wasn't being filled completely, (the array is initialized to size 36 and 36 characters are read from the file using fread) so it was printing out a random character assigned to the 36th array position. Except the character never changes, (always a $ for record 2, H for record 3, l for record 4 if i remember) and I've tried reducing the array size or the number of character read and it's the string that gets altered, the random character always remains. I figure the problem must be in the print_records function (appending seems to work no problem). Anyway here is my print records and appending records code.
Code: /*
- Prints a single record stored in the file pointed to by ifp.
*/
void print_record(FILE *ifp, int record) {
[Code]......
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Mar 8, 2013
Code:
#include <stdio.h>
#include <stdlib.h>
int main (int argc, char *argv[])
{
char buffer[256];
FILE * myfile;
myfile = fopen("read.txt","r");
[Code]...
I also got an error in printing wherein the data in read.txt is "Hello" newline "World" and my program prints world twice.
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Mar 30, 2014
I know that returning to main() is not a good idea but how will I loop the program to go back to the position selection when the voter is done voting for the last position.
when I run the program it seems fine. getting the votes from President to PRO Position is fine. The problem is how will the next voter vote without losing the vote (tally) of the previous voter?
FLOW:
SELECT POSITION (a-e) ---> SELECT A CANDIDATE (a-c) ---> (this goes on until the position of PRO) ---> ( then go back to the POSITION SELECTION)
After every vote there is a case statement for which I can choose to vote for the next position, quit, or show results (and after showing the results it will go to the next position to vote)....
#include<iostream>
#include<string>
#include <conio.h>
using namespace std;
int pca=0,pcb=0,pcc=0,ptv=0;
[Code] .....
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Mar 17, 2013
Right now I'm working on an assignment where I need to take the data from on file encrypt it by adding 5 to each byte and then save it to a user specified location. I think I'm close to having it done but I've run into a hick up. After I get the user input for where the encrypted data should be saved the program seems to never end. This is the code I have so far
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
ifstream input;
ofstream output;
[Code]...
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Jan 8, 2014
How can I read contents of a file from the last character? Can I use a loop?
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Jan 30, 2015
I need a sample program to read contents of any xml file using CPP.
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Dec 30, 2013
#include<iostream.h>
#include<conio.h>
#include<stdlib.h>
#include<string.h>
#include<fstream.h>
#include<graphics.h>
void input();
void output ();
[Code] ....
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Apr 24, 2015
HTML Code:
So I insert values from a vector into a list and into a multiset, and I noticed zero is added to their contents! I had to do a whole lot of debugging to find out where the error was, how can i stop this thing? Code which generates such error...
infact i checked the content of vector ups to be sure that there was no zero in it, but after loading into list combi_t * head, it seems like there was a zero added and this is giving me errors when i call function master_roller...
Code:
void ins(combi_t * &testa, int &numero, int &num, int &no)
{ // if (ricerca(testa, numero) == 0)
//{
combi_t *temp = new combi_t;
temp->val0 = numero;
temp->val1 = num;
temp->val2 = no;
temp->nextPtr = 0;
[Code] ....
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Nov 22, 2013
The aim will show on the screen but does not show the contents of a file on the screen different shows.
Code:
#include <stdio.h>
#include <conio.h>
main() {
char filename[100];
double xx;
int ii, kk;
[Code] .....
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Apr 15, 2014
I have a character pointer that points to 4000 bytes of valid data. I need to write these valid contents pointed to by this pointer into the file. I am looking for the most optimized way of doing this. I am using the below logic which seems trivial. Any better approach to accomplish the same?
/* length is the number of valid bytes of data */
void parse_contents(const char *data, int length) {
int j = 0;
char path[1024] = "/tmp/data.xml";
FILE *fp = NULL;
fp = fopen(path, "wb");
[Code] ....
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Nov 17, 2014
I have a program that's not doing what I want it to do. This is the assignment:
The nth term of the sequence of triangle numbers is given by, tn = 1/2 n (n+1); so the first ten triangle numbers are:
1, 3, 6, 10, 15, 21, 28, 36, 45, 55,...
By converting each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value. For example, the word value for SKY is 19 + 11 + 25 = 55 = t10. If the word value is a triangle number then we shall call the word a triangle word.
the 'words.txt' has a bunch of words in this format:
"ABSTRACT"
"YOUTH"
there's about 1000 words in that format.
And for any triangle words I find, I put it into another text file which I called triangle.txt.
Now for my program, it pulls the 'words.txt' file just fine but it doesn't recognize any of the words in the file as triangle words.
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <cmath>
#include <cstdlib>
int getCharValue(char a);
double sum1(std::string name);
[code]....
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Jan 10, 2013
How does one go about copying one binary FILE variable to another in C++? Say I have the following:
FILE* tempFile; //is a binary file and assume already filled with contents
FILE* localFile;
tempFile, as the name implies, is stored in a temporary directory (AND has a randomized temp name) within Windows and I want to copy its contents to another file with a predefined name that is within a valid local directory (e.g. C:UsersuserMy Documents est.exe). What do I have to use?
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Oct 18, 2014
Having some trouble with an assignment. Here is the prompt. Write a program that reads the telephone.dat file and displays its contents on the console. The program should allow the user to add new entries to the file.
I have saved the file into a resource file within visual studio and I am trying to run the code to where the file will be shown when I run the program. I know that the program is running and the file is there because if i misspell the filename it will give me the error message. I don't know how to make the contents of the file display. Here is what I have so far.
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main() {
ifstream inputFile;
[Code]...
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May 12, 2013
So I am working on a FUSE filesystem and I currently have the need to load the contents of a text file into an array.
My array initialization looks like: char array[max_entries][PATH_MAX] = {NULL}
The reason I want to pass it by reference is that I want my function to return two values essentially. One a specific char* and the other an array like I initialized. My function proto type looks like:
char* load_meta(char* list[max_entries][PATH_MAX], char* path, int mode);
How I'm trying to call the function:
someChar = load_meta(&array, path_name, 1);
Within the function I try to edit the array by deferenceing it once, like this:
strcpy(*list[i], file_entry); // This seg faults
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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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