C/C++ :: Determining Length Of Array Read From File
Feb 16, 2015
i have to read a file with between 5 and 10 pairs of numbers, each on a different line. i can read the file, and wrote something to save the length of the file as a variable, but when i use it i start returning crazy data. the problem is in the do while loop and i want to change the i< in the for loop to "lines" so the code stops when the last digit is read. if i use i<10 the file has extra digits is the file is only 8 or 5 pairs of numbers.
FILE *Fpointout;
FILE *Fpointin = fopen ("test.txt","r"); //read this one
Fpointout = fopen ("out.txt","w"); //write this one
if (Fpointin == NULL) //if no file in source {
printf ("File does not exist.
"); //tell user it is not there
[Code] .....
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Oct 24, 2013
char A[]={}; this is the array in c++ of unknown size, now I want to enter some alphabets via loop and want to be the no. of elements i entered the size of the array. .
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Dec 8, 2013
I am trying to extract the numbers from Numbers.txt, and then put them in the correct file, either Odd.txt or Even.txt, depending on what they are. And I have gotten to a point where I am not sure what to do; right now it just reads Numbers.txt and then the program ends.
#include <iostream>
#include <fstream>
#include <string>
[Code].....
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Oct 17, 2014
I have to make a program to read a file with strings and determine if they are palindromes. The problem is that the program says that they're all palindromes.
int main() {
ifstream inFile;
ofstream outFile;
inFile.open("in.data");
outFile.open("out.data");
if (!inFile || !outFile) //to display error if input files are invalid
[code]....
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Oct 13, 2014
I am trying to write a function that determine if a file in a directory is of a gif/bmp/png/jpg extension. Right now I think I have correctly written my code all the way up to listing the files in the directory and opening them in binary mode.
Now, I am struggling with figuring out how to determine what extension the image is. Right now i am just focusing on writing my "bool isGif();" function... To determine if a file is a .gif extension using binary, the first 6 bytes of the file will contain either GIF87a or GIF89a.So, to do this I would read the first six bytes of the file using the function below, correct?
fin.read((char *) &a_file, 6)
Then, once I read in the first six bytes how would I conditionally compare it to determine if it is a .gif? Would I just use
if(fin == "GIF87a II GIF89a) {
\do something here
}
Because that doesn't seem to be working...
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Oct 10, 2014
I want to read a string of unknown length from stdin. I tried to follow the approach from this link. URL....My code is like this:
#include <iostream>
#include <string>
using namespace std;
int n;
cin >> n;
cout << "The value of n is " << n << endl;
}
[code]......
What I have noticed is that if I take integer input from cin (cin >> n;) in the above code before getline, the control does not stop on getline to take str as input from the console. If I don't do (cin >> n) before getline then the control stops on getline and takes the string as input.What is the best way to read from console multiple strings of unknown length in combination with the integers?
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Apr 30, 2013
so basically my project goes like this:
Write a C++ program that reads in two positive integers that are 20 or fewer digits in length and outputs the sum of the two numbers.
Your program will read the digits as values of type char so that the number 1234 is read as four characters '1', '2', '3' and '4'. After they are read into the program, the characters are changed to values of type int. The digits will be read into a partially filled array and you might find it useful to reverse the order of the elements in the array after array is filled with data from the keyboard.
Your program will perform the addition by implementing the usual pencil and paper addition algorithm. The result of the addition is stored in an array of size 20 and the result is written to screen. if the result of the addition is an integer with more than maximum number of digits(that is more than 20 digits) then your program should issue a message saying that it has encountered "integer overflow".
You should be able to change the maximum length of the integers by changing only one globally defined constant. Include the loop that allows the user to continue to do more additions until the user says the program should end. What I have so far is
#include <iostream>
#include <cstdlib>
using namespace std;
void reverseArr(int a[], int liu);
void addLargeInt(int a1[], int liu1, int a2[], int liu2, int sum[], int& liu_sum);
int main() {
cin.get(next);
[Code]...
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Nov 15, 2014
I'm finishing up my first semester as a Computer Science major, but I'm struggling with programming.
I need to read a file into a 2D array.
Here is what the file contains (90 characters):
S
R
R
S
R
R
R
R
S
....
Here is my current code:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
[Code]....
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Jul 4, 2013
I need to do a program that reads a file, that contains something like this:
8 2 3 4 2
5 6 1 3 4
3 1 4 6 7
7 2 4 1 3
3 2 1 6 8
and put in a array[][] in the program..I did this:
int main(){
using namespace std;
int size=0;
char line[1300];
FILE *file;
char path[50];
int l=0,c=0;
[code].....
But when i print A[3][3], it does not contain the correct value, but I strange value, like -36893488147419103000 .My idea was to pass line by line of the file, including the values that were not " ", to get only the numbers.
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Apr 11, 2014
I can't get the values correctly parsed.
Code:
float **get(int sizeX, int sizeY) /* Allocate the array */ {
float** ary = new float*[sizeX];
for(int i = 0; i < sizeX; ++i)
ary[i] = new float[sizeY];
return ary;
[Code] ....
test.txt (without the comments).
Code:
2 3 // columns and rows of 2D array
0 0
1 1
2 2
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Jan 30, 2013
here is my code, I'm trying to read a .txt file into a 2D array... what's wrong with my code?
Code:
#include <stdio.h>
#define INPUT_FILE_GET_NAMES "names.txt"
#define INPUT_FILE_GET_SALES "sales.txt"
#define MAX_ROWS_NAMES 25
#define MAX_COLS_NAMES 20
#define MAX_ROWS_SALES 25
#define MAX_COLS_SALES 6
//Function Declarations
char getNames(char namesArray[][MAX_COLS_NAMES], char filename[]);
[Code]...
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Feb 25, 2013
I wanna read a txt file like this
1.00518 2.01903 3.01139 4.01343 5.02751 5.99913 7.00011 7.99851 .....
and fill the array P[i][j] with the data.
I try to use
if (myfile.is_open()) {
//for (int i = 0; i < 1; i++)
//{
getline (myfile,DMArray[0]);
cout << DMArray[i] << endl;
//}
myfile.close();
}
But this read the data into a string. How should i do with this string. Besides I know the dimension of the data I am reading.
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Apr 11, 2013
So the premise of my code is to read in a 2d array from a .txt. The array is a game board but the first two lines are what determine the size of the board. After i read it in i want it to find wherever te character "U" is, and then display the array but only showing U and whats around it. Problem is i cant get the array to print the right size and the code for displaying the U is not working either.
ifstream inputFile;
int boardSizeRow;
int boardSizeCol;
inputFile.open("C:UsersMichaelDesktopfileboard2.txt");
inputFile >> boardSizeRow;
inputFile >> boardSizeCol;
inputFile.get();
[Code]...
FILE:
20
20
WWWWWWWWWWWWWWWWWWWW
W GO W W
W WW w S W
W H W GW w W
WPW WW G W
WK W W
W W W W w w W
WK WU W
SW w w W
W W
w W G W
G W w W
D wwwww W
K w D W
w w W w w W
ww w WWWWWWW
G w W
ww w S w W
WWW G W
WWWWWWWWWWWWWWWWWWWW
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Oct 22, 2013
determining if a value entered in loop is an odd or even number. Also, the value can't be int because it may be a decimal value(therefore i cant use the if(x%==0).
I need to replace the if(value%2 ==0) else num_even++ statement in my code with something else that will work with float to determine odd vs even.
#include <iostream>
using namespace std;
int main() {
int num_values;
float sum_values = 0;
int num_neg_values = 0;
int num_pos_values = 0;
[code]....
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Mar 3, 2013
In a program, I have a text file (called MyDictionary.txt) which has thousands of words in alphabetical order. I need to make a C program that reads in this text file and then makes an array called char Words[# of total words in the text file][length of longest word].
Aarhus
Aaron
Ababa
aback
abaft
abandon
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Nov 15, 2014
I am currently working on a problem where I read a file into a 2D array, and display data. If you saw my code earlier, this is the same problem, but I am now further along.
The file (90 characters) looks like this:
S
R
R
S
R
R
R
R
S
S
....
The "R" resembles rainy days, the "S" resembles sunny days, and the "C" resembles cloudy days. There are 90 characters in the file. The first 30 are for the month of June, the next 30 are for the month of July, and the last 30 are for the month of August. The 31st day of the months are NOT included.
I read the data into a 3 x 30 array, where the row indicates the month (0 = June, 1 = July, 2 = August) and the column indicates the number of days in each month.
Now I need to create a function that creates a report and displays, for each month AND for the whole 3 month period:
1) The number of rainy days
2) The number of cloudy days
3) The number of sunny days
4) Which of the 3 months had the largest number of rainy days
Here is my code so far:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int MONTHS = 3;//Number of months
[Code] .....
There are no compiling errors, but I am not getting the data I want. My rCount and cCount variables end up being 0, and my sCount variable is 90.
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Apr 4, 2014
Perhaps my original wording on this was confusing so I will ask a different way.
if I have a text file called
data.txt
and it has the following in it.
12345
67890
12345
67890
how would i read this information into an array called
int data[4][5]
This is in C.
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May 3, 2014
Assume you want to read from a file and place the data from the file into an array. The array can hold 10 integers. The file may contain any number of integers with 1 integer per line. Fill in the missing loop test condition so that we will read from the file until either end of file occurs or the array is full. Note we are using cin to read from the file since input redirection is being used.
cin >> temp;
arrayIndex = 0;
while ( _____________________________________) {
array[arrayIndex] = temp;
arrayIndex++;
cin >> temp;
}
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Dec 9, 2013
I need function to determine where to place new element in sorted array. I want to use binary search to find index where element should be placed, when push all others.
Prototype should be something like
int WhereToPlaceElement(ElementType hash); // uses private atribute ElType** elements
I have tried my best to write, but all tries ended in inf loops and reading invalid locations of array.
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Apr 16, 2013
I'm working with arrays that might have NULL bytes in them and I'm wondering how to determine the length of the array or store it somewhere with the array (strlen() won't work because of the NULL, right?).
I've found advice like store the length of the array in the first byte of the array, but since sizeof(size_t) is 8 should I leave the first 8 bytes for the length?
Would it be better do define my own structure which would store the array and its length? What's the usual way these things are handled in practice?
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Feb 9, 2014
I was reading in a book I had about C that an array has at the very end a "null character" signifying the end of the string inside it, "/o". So that made me think, "I guess one needs to declare arrays as having 1 extra space than one expects the array to need. I wonder what will happen if I exceed the array length?" So I made a program to test it out. Here is the program/results:
Code:
#include <stdio.h>
int main(void){
char name[3];
printf("
What's your name?
");
scanf("%s", name);
}
[code]....
As you can see my name was able to fit in the array somehow even though I only allocated 3 bytes to the array. I tried again using my legal first name, Benjamin, and it was still able to fit. How is the array able to hold my name when I declared it as only having 3 bytes?
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May 24, 2013
i having a code to pass in array as argument, but the length returned is 1. This is not match with the array size.
int Getsize(int Array[])
{
int len = sizeof(Array)/sizeof(int);
cout << len << "
";
}
int main()
{
int X[] = {45, 12, 54, 83, 41, 36};
getsize(X);
}
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Sep 7, 2013
I can't find any method of retrieving the length of an array except for doing this:
string first[] = {"a","be","see"};
int length = sizeof(first)/sizeof(first[0])
This is a very unconventional way of getting the length of an array.
first->length() would return 1 because it returns the number of letters in the first element of the array (which actually makes no logical sense).
first.size() would return 1 aswell as it's practically the same thing.
Since getting the length of an array is such a fundamental feat, how come I can't find a decent method of doing it?
Is there no buildt in method for this? If there is not, why has it not been implemented in the std?
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Jun 16, 2014
I have a program with the following code, and I need to be able to either change the value of any or all of the strlen or to replace one or all with a temp array value. All values of the expression are arrays.
if (::strlen(tc_buf) + ::strlen(maxtime_buf) + ::strlen(" ") < sizeof(localBuf))
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Jan 23, 2015
I'm trying to make an application and I need the length of the array of a struct. Like this:
struct myStruct {
int integer;
};
myStruct struct[] =
{
1,
2,
};
I want to get how many ints are in the array...
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Mar 17, 2014
code:
/part of main function
int *A=NULL;
//load from file
load_from_file(A, &next);
printf("next=%d
",next);
getchar();
printf("A[%d]=%d
",0,A[0]);getchar();//here program crashes
}
[code]....
I initialize array A with NULL in main, and I "load" it with elements from a file. The code without function is working. But when I tried to use a function as above, my array crashes!!!
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