C++ :: Binary File - Replace Data At Specific Point?
Nov 28, 2014
I'm making a binary file that has 100 "empty spaces", and then I want to rewrite specific place with info, however it always writes the info at the end of the file, no matter what I try to get position before I call write() it tells me correct position...
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");
This code is working totally fine. Right now, I'm trying to update a specific data from the student info. Let's say I'm trying to update my student number of Daniel. So, in this case, I want to replace 6744590 to some other student number. I think I have to use fseek() or rewind() and use fputs() but, I don't know how I should decide where to look.
I wrote a code to read a specific amount of data from file until terminating set is reached. however the code does what its supposed to correctly until it reaches the 5th loop it justs stops responding. I've checked the reading file and all elements are correct in the file.
Code: int main(void){ FILE *file1; FILE *file2; FILE *file3;
I'm not the best at C but I'm trying to write a C function that basically opens a text file with assembler language does a syntax error check on it and then converts the binary data into hex.
This is my code so far:
Code:
#include <stdio.h> #include <string.h> int main(void) { FILE*fname; char prompt; char filename[15]; char text[100]; printf( "Please enter the name of the file you wish to open: " );
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;
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;
I found the following code in [URL] ....., that send .TXT files perfectly to php script in my server using Wininet, but when I insert a .BMP file, this file (.BMP) is correctly created and named in server side, but it is empty! I read that is necessary implement base64 encode for work properly, so how would?
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() ??
I am parsing a binary data file by casting a buffer to a struct. It seems to work really well apart from this one double which is always being accessed two bytes off, despite being in the correct place.
If I attempt to print GROSS using printf("%f", row->GROSS) I get 0.0000. However, if I change the type of GROSS to char[8] and then use the following code, I am presented with the correct number...
Code:
typedef struct example { double d; }
example; example *blah = (example*)row->GROSS; printf("%f", blah->d);
So I wrote a program to turn a binary file's data into an unsigned character array for inclusion in an executable. It works just super.
I'm wondering how I can write a program that will perform this operation on every file in a directory and all it's sub-directories so that I can I can include everything I need all at ounce.
I want to get the value of "Skateboard" on file. So I need to read 9 lines. On the 9th line, the gets() loop will stop. But, what if I only want to get the value of "Skateboard" as integer (87) and not a string? Also, is it possible to scan the value of Skateboard if it's located on a different (or unknown) line?
I can access a physical device to read a specific sector in a USB hard drive. But my question is how can I Write to a specific sector? Lets say I want to replace what is in a specific sector of a hard drive with a new data.
I created a dataset that contains an empty dataTable that has several columns , and then I created a new report that is linked to this datatable using the report wizard. In my form there is a button when clicked should fill the datatable mentioned above ( I checked if it is being filled by displaying its content in a dataGridView and by firing a messagebox that is triggered when 'datatable.rows.count > 0' ).
The reason that the datatable is initially empty is that it depends on some conditions that may alter the query used to fill it.
But finally when I load the form that has the report viewer it only has the names of the columns of the datatable and no contents. What's wrong ?
Code: #include <iostream> #include <iomanip> using namespace std; int main() { int dayNumber = 1;
[Code] ....
The code, when run, prompts the user to input an integer like this:
Code:
Day 1 Andy :>12 Bill :>7 Charlie :>15
Day 2 Andy :>5 Bill :>25 Charlie :>14 . . . etc.
Ok, so the code prompts the user to enter an integer for each of the 3 persons and then increments the "Day" and so on... When the user enters a negative value (-1, -2, etc.), the loop is broken and the program ends. Alright, everything is hunky-dory so far. 2 things which I can't figure out.
1. when the user doesn't enter anything and just hits return, the cursor drops a line and is still awaiting an input but doesn't show the prompt "Andy :>", for example. How can I get it to repeat the last prompt when the user doesn't enter anything? Like:
Code:
Day 1 Andy :> Andy :> Andy :>12 Bill :>25 Charlie :>15 . . etc.
2. When the user enters a letter or a special character, the program blows up. How can I correct this?
I've tried changing the data type for the variable used for the input, tried using getline, get, etc. With my current beginner knowledge, I'm missing something. So how can I get this to work?
The program should allow only integers to be entered, while allowing a negative number to trigger the loop to break or the program to end, and while re-prompting the last person if the user entered an invalid input.
I was given an assignment to create a simple program for traffic control. How should i output data at a specific time, for e.g a driver approaches an intersection, the yellow light will flash indicating that he needs to slow down and then the red light to stop before taking a route. is there any function i can use to output red light a few seconds after yellow light.
I'm having a bit of problem. I've set the string 'Absent' to all student in a file. However, I want to replace 'Absent' with 'present' when the correct ID assigned to a student is entered. In other words, 'Absent' will only change to 'Present' for a specific person at a time. I'm not sure how to implement this
My text file have 220 663 lines and 858 995 characters (I used Linux commands : wc to count them. If I use array to store data, I think it's too large array. But if use fstream, I dont know to access each element in stream to compare and replace. I dont know How many labels such as: A1, C- A1, AM- MNR... which I have to replace.
To replace a string in my file with another. The file contents look like the following:
abc 123 0
"abc"= The username "123"= Their password "0"= The amount in their bank
I want to change their bank amount.
But, it isn't working, nor is it even giving me an error code.
// When the user logs out, make changes to their bank string strNew = std::to_string(player.bank); // String representation of the revised player bank ifstream filein("user_accounts.txt"); // Old repository of player data ofstream fileout("user_accounts_new"); // New repository of player data
I want to remove some character in my file. too i want to replace some char to another. I know the easiest way for this job is we write final text in file. i mean we first produce sightly text then write it in file . I don't want use of temporary string.