C++ :: Writing 32 Bit Integer To 32 Bit Value In Binary
Jul 17, 2013
So, I was reading that article on binary files:
Disch wrote:
u16 ReadU16(istream& file) {
u16 val;
u8 bytes[2];
file.read( (char*)bytes, 2 ); // read 2 bytes from the file
val = bytes[0] | (bytes[1] << 8); // construct the 16-bit value from those bytes
[Code] .....
u32 would be the same way, but you would break it down and reconstruct it in 4 bytes rather than 2.
But, I don't know what he means by the part in bold text.
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May 30, 2013
Both arrays arr and pointers are the same size. I am having problems reading pointers from file into a new int array.
FILE* ky_pt=fopen("stashedclient","ab");
write(fileno(ky_pt), pointers, sizeof(pointers) );
pointerindex=lseek(fileno(ky_pt), 0, SEEK_CUR );
printf("pointerindex after writing array %d
[Code] .......
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Aug 16, 2013
I a want to write a code to convert a string into binary data for that i wrote a code its working perfectly but there is one problem , some of the binary data is written in 7bit and i want to convert it to 8 bit by adding 0 to the last.
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
[Code]....
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Mar 10, 2014
So I'm trying to write an array of integers to a binary file. He's my code:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
[Code].....
I know that it is an array of characters right now, and I will be using the reinterpret_cast when I finish my program. Anyways, when I run the executable, it only writes 1234 to the file. My assumption was that the sizeof() was not being set properly, but even manipulating that won't fix it.
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Jun 5, 2014
why I'm giving "Access violation reading location 0x336827B8" and also I was able to read my data but it's giving me weird stuff. I want to write the sorted grades and the average in a new disk file. so here's my code so far here's my code
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
int avg(int sum, int size);
void swap(int *, int *);
[code]....
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Mar 6, 2013
I am having problems either writing data to a binary file or reading from the file. Through the process of elimination I am posting the code where the data is written to file to see if I can eliminate that as an option. I know the data is being processed correctly because, through the use of another function, I can view the data.
I also know that fwrite must be including some padding because the file size ends up being 576 bytes after it is written instead of 540 bytes (the size it would be if no padding is used). Here is my struct:
Code:
typedef struct {
char teams[25];
float wins;
float losses;
float pct;
int runsScored;
int runsAgainst;
} STATISTICS;
Here is where I initialize it:
Code:
STATISTICS stats[12] = {
{"Anaheim Arrays", 0.0, 0.0, .000, 0, 0},
{"Pittsburg Pointers", 0.0, 0.0, .000, 0, 0},
{"Indianapolis Integers", 0.0, 0.0, .000, 0, 0},
[Code] ....
And here is the function that writes my data. The sA array is only used to change the scheduled games based on the variable week.
Code:
void schedule(STATISTICS stats[]) {
FILE *f;
int sA[12], week = 0, runsPerGameA = 0, runsPerGameB = 0, runsAgainstA = 0, runsAgainstB = 0;
int index, a = 0, b = 1, i = 0;
[Code] .....
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Feb 17, 2014
cant write to binary file
#include <stdio.h>
#include <stdlib.h>
typedef struct {
int number;
} something;
void main() {
int numbers[10]={1,2,3,4,5,6,7,8,10,12};
[Code] .....
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Apr 2, 2013
I am writing a double number in Binary format to the console of program A (in FORTRAN) with the following code:
Code:
REAL*8 A
A = 12.54
INQUIRE(6, name = xstring)
OPEN(1,file=xstring, access='stream',action='write')
WRITE (1) A
CLOSE(1)
And trying to read that number by program B (in C++) which is connected to program A by anonymous pipes. Following is the reading part of program B:
Code:
#define BUF_SIZE 5000
BOOL bSuccess = FALSE;
char Buf[BUF_SIZE];
DWORD dwRead;
for (;;) {
bSuccess = ReadFile( V_hChildStd_OUT_Rd, Buf, BUF_SIZE, &dwRead, NULL);
if( ! bSuccess || dwRead == 0 ) break;
}
Note: V_hChildStd_OUT_Rd is a handle to the output of program A.
After running the program although bSuccess becomes TRUE, Buf array does not include the number (12.54) that I am expecting. If I do the same process without using the binary format it works fine and I can read the number. I know somethings wrong with the writing or reading of binary data but I do not know what it is.
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Aug 5, 2013
I am trying to write down in binary format an array of unsigned int values but i get the following compilation error :
: In function ‘int CIndex(std::fstream&, std::fstream&, std::fstream&, std::fstream&)’:
./src/IndexBuilder/index.cpp:23:26: error: no matching function for call to ‘std::basic_fstream<char>::write(int*, long unsigned int)’
./src/IndexBuilder/index.cpp:23:26: note: candidate is:
/usr/include/c++/4.6/bits/ostream.tcc:184:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::write(const _CharT*, std::streamsize) [with _CharT = char, _Traits = std::char_traits<char>, std::streamsize = long int]
This is the part the is not working:
Code:
// uia is : unsigned int * uia;
// then I have allocated the space for it
// load it with unsigned int's
// k is the number of variables in my array
o.write(uia,sizeof(unsigned int)*k); But thsi should be so simple and strait forward.... in c i do it as :
Code:
fwrite(uia, sizeof(unsigned int), k , fp); but since i would need to convert fstream to FILE* i decided to do it c++ way.
and this is how i opened the file :
Code:
o.open (fileName.c_str(),std::ios::out|std::ios::binary);
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Jul 9, 2014
fstream ifs;
ifs.open ("data.str", ios::binary | ios:ut);
char *data1 = "data1";
char *data2 = "data2";
ifs.write(data1, strlen(data1));
ifs.write(data2, strlen(data2));
when i this,data2 is not going under data1, i thought each write starts on a new line?
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Mar 8, 2013
How to read and write an arbitrary number of bits from/to a file stream.
For instance, how to repeatedly read 9 bits from a file, then change to 10 bits, then 11 bits, and so on?
Obviously one way is by doing a lot of bit shifting, and masking. But honestly, I'm too dumb to get it right. Then I thought about using std::bitset and std::vector<bool>.
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Oct 20, 2013
When you have to write data on a file in binary mode multiple times (without closing the file), is the put pointer left where you ended writing the last time, or do you have to use tellp() or seekp() again and again to make sure you write at the right place?
I would have the same question about the get pointer, does he stay in place after you're done reading something (without closing the file, of course), or do you have to set it back at the right place with seekg() ??
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Aug 21, 2014
I would like to write a complete structure array to a file and read it back, recovering all the data. I have tried the following:
Code:
#include <stdio.h>
#include <string.h>
#define NUM 256
const char *fname="binary.bin";
typedef struct foo_s {
int intA;
int intB;
char string[20];
[Code]...
//---------------------------------------------------- but the mac field is reading back some random value repeatedly. Why is that? And how do I fix this?
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May 23, 2013
I wrote this code purely for educational purposes. It also learn more about how exactly things look in memory. code I have right now ( I will likely add more and change it in the future) .....
Code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <ctype.h>
[Code].....
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Aug 9, 2013
This program is basically working. I'm very knew to C++, so basically I need instructions as if you were explaining this to your grandma. I need this to loop but how to incorporate one. Basic code (while loops). Here is what I've done so far.
#include <iostream>
using namespace std;
int main () {
int i, c, k;
cout << "Please enter a number to convert: ";
cin >> i;
[Code] ....
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Jan 29, 2015
Write a C++ application program to accept a signed decimal integer as input and output the equivalent 2s complement version in 16-bit binary. Include a space between every four bits in the output string. The input will only be processed by the application if it falls in the valid range that can be represented in 2s complement format with 16 bits. The range of a decimal number from - to + is -32768 to 32767.
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Oct 25, 2013
I am trying to assign the integer value to unsigned char array. But it is not storing the integer values. It prints the ascii values. Here the code snippet
Code: uchar uc[100];
for(i=0;i<100;i++)
{
uc[i] = i;
}
The values which are stored in uc[] is ascii values.I need the integer values to be stored in uc[]. I tried to do it with sprintf. but the output is not as expected. if I print the uc[i] it should diplay the value as 0,1,2....99.
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Jun 15, 2014
changing a 9 digit integer into a new 9 digit integer through simple mathematical operations. For example, I need to change 123456789 into the new digit 456123789. Sometimes I need to change a 9 digit integer into an 8 digit integer. An example is 789062456 into 62789456. I can ONLY use simple mathematical operations (addition, subtraction, multiplication, division and modulo).
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Oct 15, 2014
Complete the function myitohex so that its converts 8-byte integer to string based hexadecimals.
Ex: printf("0x%s",myitohex(64,hex)); should printout "0x40" on the screen
char *myitohex(uint8_t i, char *result){
???
return result;
}
I wrote:
#include <stdio.h>
#include <stdint.h>
char *myitohex(uint8_t i, char *result){
*result = i + '0';
[Code] ....
0xp gets printed out which is wrong. I think *result = i + '0'; is wrong. What changes should i do on this row ?
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Dec 6, 2013
Following is the program I wrote it basically takes 9 inputs and then save them into binary file. then print out the data stored in binary data and find inverse of it then print the inverse out. but its stuck in a loop somewhere.
Code:
#include <stdio.h>
int main() {
int a[3][3],i,j;
float determinant=0;
int x;
FILE *fp = fopen ("file.bin", "wb");
[Code] .....
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Dec 6, 2014
I'm using maps and writing files for the first time and I get a crazy compiler error when I try to compile the following code.
//map is named schedules
// saveSchedule() is a member of the Schedule class that writes a vector of objects to disk, or is supposed to
ofstream newFile("sched.txt");
map<string,Schedule>::iterator in;
[Code] .....
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Mar 17, 2014
I'm working on a 10 week project, and this is a small issue that I can't fix myself.
///////////////////////////////////////////
/* WRITE SINGLE CHAR */
///////////////////////////////////////////
void LCD_Write(unsigned char c) {
while(!(UCSR1A & (1<<UDRE1))); // 0x20 (1<<UDRE0)
UDR1 = c;
Delay(5);
[code]....
This project is a Atmega 2560 connected to a serial GLCD screen.I've got serial communication working perfectly.Now as you can see I wrote a function that sends 1 single character to the UDR1.I wrote a function that uses this first function for sending entire words (strings).All of this works great.
Next challenge is writing a "int byte" to the GLCD screen.In this case the variable "voltage" has a value of 100.I'd like to write that 100 to the serial display via the uart.But whenever I do this the screen reads this 100 as a ascii decimal number... (= d)
I've tried things like
LCD_PrintStr("voltage"); (Result: The word voltage shows up on the screen)
LCD_Write(voltage); (Result: write ascii letter for dec 100 (= d ))
[URL]
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Sep 9, 2014
I am executing below sample program
Code: #include<iostream.h>
#include <fstream.h>
using namespace std;
int main()
[Code]......
when i am counting the lines using wc command it is giving 1 instead of 2.
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Nov 3, 2014
I'm writing a program using Huffman algorithm to compress text file. I have tested my program by just printing the printing ASCII character to file and it worked fine. However, now I have to implement using bits and my program doesn't work. It seems like I'm not reading or writing the right bits. Here is the result of my testing:In the input file I put abc the input file to compress it. Then I uncompress it the out out is aaa. Below is a snippet of how I read and write bits
Code:
class BitInput {
istream& in; // the istream to delegate to
char buf; // the buffer of bits
int nbits; public:
BitInputStream(istream& s) : in(s), buf(0), bufi(8) { }
[Code] ....
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Dec 11, 2011
I have a question about an issue I am having on my final project. Within my ItemEntry.cs form, I am trying to get the application to append the already existing .txt file, rather than prompt the user to replace it. I can't seem to get the StreamWriter and FileStream to allow the user to write to the file.
Code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
[Code] .....
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Sep 28, 2013
I am trying to write a structure to a file. Example say the structure has two variables x and y . I want to write a function which modifies these variables and stores the modified version on a file. Such that next time I call the function . it has the values from the previous write. Here's an example of my code .
Code:
// initialize the structure struct->x = 0, struct->y = 0
File *fp = fopen("filename", "r+");
struct MYSTRUCT mystruct = (struct MYSTRUCT*)malloc(sizeof(MYSTRUCT))
//check
fread (mystruct, sizeof(MYSTRUCT), 1, fp);
// do some calculations.
fwrite(mystruct, sizeof(MYSTRUCT), 1, fp);
fclose(fp)
//return some value
}
The problem is that each time I run the program it shows the initialized value of the variables and not the value from last write. I guess the write isn't successful because when I open in w+ mode. i get the error file could not be opened and then i have to delete the file and re create it....
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