I was given a binary file that I need to convert to a readable text file using C and Linux. The code below was partially taken from this site.
I have tried several algorithms I have found but none seem to work.
unsigned char buffer[1000];
FILE *input;
FILE *output;
int n = 0;
int count = 0;
input = fopen("memdb","rb");
output = fopen("output.out","wb");
while(!feof(input))
{
n = fread(buffer,1,1000,input);
count += n;
fwrite(buffer,1,n,output);
}
fclose(input);
fclose(output);
Your code performs an exact copy of the binary contents of memdb to output.out. No conversion to readable text at all. Note that while(!feof(input)) is not a correct way to test for end of file, but in your particular case it does not pose a problem.
Your goal is unclear:
what do you mean by readable text file?
what kind of data does memdb contain?
do you want to convert non ASCII data to some alternate form that is more readable by a human being?
Here is an alternative that produces a hex dump:
/* copy binary file memdb as hex, returns the number of bytes or negative for error */
int copy_memdb(void) {
FILE *input;
FILE *output;
int c, count;
input = fopen("memdb", "rb");
if (input == NULL) {
return -1;
}
output = fopen("output.out", "w");
if (output == NULL) {
fclose(input);
return -2;
}
count = 0;
while ((c = getc(input)) != EOF) {
if (count++ % 16 == 0) {
putc('\n', output);
} else {
putc(' ', output);
}
fprintf(%02X", c);
}
if (count > 0)
putc('\n', output);
fclose(input);
fclose(output);
return count;
}
Related
I wrote this code where I generate random integers in a large quantity and store them in a txt file. it works if I input up to 49 integers
but after that it does not read any further from the file or the file don't accept any further I don't know please help me
this is the code
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
FILE *fptr;
int num, n;
fptr = fopen("integers.txt", "w");
if (fptr != NULL)
{
printf("File created successfully!\n");
}
else
{
printf("Failed to create the file.\n");
return -1;
}
printf("Enter some integer numbers [Enter -1 to exit]: ");
scanf("%d", &n);
while (n != 0)
{
num = rand();
putw(num, fptr);
n--;
}
fclose(fptr);
fptr = fopen("integers.txt", "r");
printf("\nNumbers:\n");
int count = 0;
while ((num = getw(fptr)) != EOF)
{
printf("%d\n", num);
count++;
}
printf("\nNumber of elements in the file %d",count);
fclose(fptr);
return 0;
}
You have following problems:
As you're writing binary data, the file needs to be opened with "wb" and "rb" (b stands for binary). Othwerwise certain unwanted text substitutions will take place.
If one of your random numbers turns out to be -1, the read will stop prematurely because EOF has the value -1. Therefore you need to do the end of file check with the feof function instead of comparing the value read with EOF.
fptr = fopen("integers.txt", "wb"); // <<< open with binary mode "wb"
...
fptr = fopen("integers.txt", "rb"); // <<< open with binary mode "rb"
printf("\nNumbers:\n");
int count = 0;
while (1)
{
num = getw(fptr);
if (feof(fptr)) // end of file reached => stop the loop
break;
printf("%d\n", num);
count++;
}
BTW:
The documentation of getw concerning the return value is pretty misleading, especially the part "A return value of EOF indicates either an error or end of file" seems wrong to me. getw can read -1 values (0xffffffff) without problems.
I have a file .txt containing some values formatted like this:
0,30,25,10
Now, I open up the file and store it into an array
char imposta_tratt[300];
FILE *fp;
fp = fopen("/home/pi/Documents/imposta_trattamento.txt", "r");
if (fp == 0) return;
fread(imposta_tratt, sizeof(imposta_tratt), 1, fp);
fclose(fp);
Now I expect to have the array filled with my data. I have the values separated by a , so I go on and parse it:
const char delim[2] = ",";
int t=0;
char *token = strtok(imposta_tratt, delim);
while (token!=NULL){
strcpy(tratt[t],token);
token = strtok(NULL, delim);
tratt[t]=token;
t++;
}
Here, referring to what's in the file .txt, I expect to have tratt[0]=0; tratt[1]=30; tratt[2]=25; and so on, but seems like I am missing something since it's not like this.
All I want is to have the values of the txt file stored in single variables. Can someone help?
What you are trying to achieve can simply be done using fgets():
bool read_file_content(const char *filename, const size_t tsizemax, int tratt[tsizemax], size_t *tsize, const char *delim)
{
// Attempt to open filename.
FILE *fp = fopen(filename, "r");
if (!fp) return false; // Return false upon failure.
// Try to read one line. If you have more, you need a while loop.
char imposta_tratt[300];
if (!fgets(imposta_tratt, sizeof imposta_tratt, fp)) {
fclose(fp);
return false;
}
*tsize = 0;
char tmp[300]; // Temporary buffer. Used for conversion into int.
char *token = strtok(imposta_tratt, delim);
while (token && *tsize < tsizemax) {
strncpy(tmp, token, sizeof tmp);
tratt[(*tsize)++] = atoi(tmp);
token = strtok(NULL, delim);
}
fclose(fp);
return true;
}
const char *filename: The file you want to parse.
const size_t tsizemax: The maximum size of your tratt array. It is important to control the size, otherwise your code will have buffer overflow (think of when your file has more than 100 tokens, for example).
int tratt[tsizemax]: The array that will hold the values.
size_t *tsize: The number of tokens read (used in combination of tsizemax).
const char *delim: The delimiter(s), in your case a ,.
This is your main():
int main(void)
{
int tratt[100];
size_t size = 0;
if (!read_file_content("in.txt", 100, tratt, &size, ",")) {
puts("Failed");
return 1;
}
for (size_t i = 0; i < size; ++i)
printf("%d\n", tratt[i]);
}
Output:
0
30
25
10
Suppose "in.txt" has contents
0,30,25,10
The below program uses fscanf to read the integers into the tratt array, one-by-one. As we read integers using fscanf, we make sure it's return value is as expected. If not, we close the file and exit. In the event that the return value of fscanf is not as expected, the program also prints which type of error occurred. Currently, if any error occurs, the program stops. However, you can make the program behave differently depending on the error that occurred if you like.
As output, the program prints all of the integers read into the tratt array. The output is
0
30
25
10
Now this program assumes we know the number of elements we want to read into tratt. If we do not, we could allow for dynamically allocating more memory should the array need more elements or perhaps "in.txt" could contain a data structure, say, at the beginning/end of the file that records information about the file, such as the number of numbers in the file and the data type (a binary file would be best suited for this). These are just a couple of the possibilities.
A better approach might be to read characters in one-by-one (say, using getc) and use strtol to convert a sequence of character digits to a long int (I would have taken an approach similar to this).
Nevertheless, this approach is more succinct and should suffice.
#include <stdio.h>
#include <stdlib.h>
#define FILE_NAME "in.txt"
#define MAX_LEN 4
int main(void) {
int i, tratt[MAX_LEN];
FILE *fp = fopen(FILE_NAME, "r"); /* open file for reading */
/* if cannot open file */
if (fp == NULL) {
printf("Cannot open %s\n", FILE_NAME);
exit(EXIT_FAILURE);
}
/* read integer, checking return value of scanf as expected */
if (fscanf(fp, "%d", &tratt[0]) != 1) {
if (ferror(fp))
printf("fscanf: read error\n");
else if (feof(fp))
printf("fscanf: end of file\n");
else
printf("fscanf: matching failure\n");
fclose(fp);
exit(EXIT_FAILURE);
}
for (i = 1; i < MAX_LEN; i++)
/* read comma plus integer, checking return value of scanf */
if (fscanf(fp, ",%d", &tratt[i]) != 1) {
if (ferror(fp))
printf("fscanf: read error\n");
else if (feof(fp))
printf("fscanf: end of file\n");
else
printf("fscanf: matching failure\n");
fclose(fp);
exit(EXIT_FAILURE);
}
fclose(fp); /* close file */
/* print integers stored in tratt */
for (i = 0; i < MAX_LEN; i++)
printf("%d\n", tratt[i]);
return 0;
}
Alright, so basically what I have to do is change all the numbers of a text file to dollar sign, I know how to scan for the specific character but I am stuck on how to replace that specific character with dollar sign. I don't want to use fseek or any library commands, how do I proceed and why isn't my code working?
#include<stdio.h>
main()
{
FILE* fptr;
char filename[50];
char string[100];
int i;
printf("Enter the name of the file to be opened: ");
scanf("%s",filename);
fptr=fopen(filename,"w");
if(fptr==NULL)
{
printf("Error occurred, try again.");
return 0;
}
fgets(string,"%s",fptr);
do
{
if(string[i]>='1' && string[i]<='9')
{
string[i]='$';
}
}
while(i!=100);
fclose(fptr);
}
There are basically two approaches at first glance, the first is to use fseek() and the second to read the file in its entirety and replace the characters to your criteria and finally write that in one shot. You can choose either of the approaches depending on your need. For large file you should prefer the former and for small file you can prefer the latter.
Here's an example code of the former:
#include <stdio.h>
int main() {
// Open the file
FILE *fptr = fopen("input.txt", "r+");
if (!fptr) {
printf("Error occurred, try again.");
return -1;
}
int c;
// Iterate through all characters in a file
while ((c = getc(fptr)) != EOF) {
// Check if this current character is a digit?
if (c >= '0' && c <= '9') {
// Go one character back
if (fseek(fptr, -1, SEEK_CUR) != 0) {
fprintf(stderr, "Error while going one char back\n");
return -1;
}
// Replace the character with a '$'
if (fputc('$', fptr) == EOF) {
fprintf(stderr, "Error while trying to replace\n");
return -1;
}
}
}
// Flush the changes to the disk
if (fflush(fptr) != 0) {
fprintf(stderr, "Error while flushing to disk\n");
return -1;
}
// Close the file
fclose(fptr);
return 0;
}
Full Edit:
I am getting frustrated, I don't know what am I doing wrong in here
I still have so many stuff to do in the code but I can't even open a file to continue my work.
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
void main()
{
char letter;
FILE *fp;
fp=fopen("C:\\Users\\LENOVO\\Desktop\\data.txt","r");
if(fp==NULL)
{
printf("error");
getch();
exit(1);
}
while(fscanf(fp,"%d",&letter)!=EOF)
putchar(letter);
getch();
fclose(fp);
}
Picture of the path: http://imgur.com/a/YwFYy
Still prints error
Ok, firstly let's take a look at your file path. There are two ways to acces a file from your local storage:
relative addresses if the file has the same root folder as your application
absolute addresses if the file is in a determined place on your machine's storage
I see that you are trying to use an absolute address to read from your file. Your path is correct but you have to take care about string formatting in C because the \ character could be interpreted as something else.
I would suggest to use this instead ( double back-slash )
input=fopen("C:\\Users\\LENOVO\\Desktop\\data.txt","r");
This will prevent string formatting interpretations.
Secondly, EOF is just a predefined macro constant and i think it is equal to -1 so your while(! (-1) ) code is not a good ideea for reading until the end of the file.
In order to read from a file until you reach the its end i would consider this property of fscanf() :
fscanf() returns EOF when it reaches the end of the file.
while(fscanf(input,"%ch",&letter) != EOF) {
putchar(letter);
}
This way of reading from a file should do the job.
To read everything from a text file and store its contents into a buffer:
First, you should count how many characters there are in the text file:
size_t get_file_len(FILE *fp)
{
size_t num = 0;
while (fgetc(fp) != EOF)
num++;
return (fseek(fp, 0, SEEK_SET) == 0 ? num : 0);
}
Then allocate memory for a buffer large enough and read all the characters:
char *load_text(const char *path)
{
char *buf = NULL;
FILE *fp = NULL;
size_t num = 0;
size_t i = 0;
int c = 0;
/* open the file in text mode */
fp = fopen(path, "r");
if (!fp)
return NULL;
/* if the file was empty or if an error occurred, return error */
if ((num = get_file_len(fp)) == 0) {
fclose(fp);
return NULL;
}
buf = malloc(num + 1);
if (!buf) {
fclose(fp);
return NULL;
}
while ((c = fgetc(fp)) != EOF)
buf[i++] = (char)c;
/* ensure that the string is null-terminated */
buf[i] = '\0';
fclose(fp);
return buf;
}
Also, in C, all escape sequences begin with a '\' (backslash), so if you wanted to write a backslash in a string or a char you should write it as a '\\' (double backslash):
input=fopen("C:\\Users\\LENOVO\\Desktop\\data.txt","r");
pretty simple here :
while(!feof(input)){
fscanf(input,"%c",&letter);
putchar(letter);
}
and remember to close file using fclose(input);
I searched through and didn’t get a quite working answer. Although I know that still there might be plenty of answers out there. Honestly I couldn’t find it as I am a beginner to C/C++ .
My problem is I have a text file which has data on it separated by pipes('|'). Actually a log file. In each entry things are separated by pipes('|') and each entry is separated by new line('\n')its really lengthy. So I wanted to do is that when user gives a sequence sequence=[2,5,7] the function should be able to read that array and give only the things starting with that pipe position. So here It should give 2nd ,5th, and 7th things in to a text file. down here is the code I used. It doesnt work for some reason I can't find. It gives the resulting text file printed out only with the '\n' and no more.Its more thant the entries in the file too.
minorSeparatorChar is the charactor given as '|'
majorSeparatorChar is the charactor given as '\n'
inFile Input text file
outFile output text file
minSepCount minor separator count
majSepCount major separator count
sequence is a global const int array
void getFormattedOutput(char * inFile, char * outFile, char minorSeparatorChar,char majorSeparatorChar){
FILE *readFile,*writeFile;
int charactor=0, minSepCount=0, i=0,majSepCount = 0;
int flagMin = 0;
char charactorBefore = NULL;
readFile = fopen(inFile,"r"); // opens the file for reading
writeFile = fopen(outFile,"w"); // opens the file for writing
if (readFile==NULL || writeFile == NULL){
printf("\nFile creation is not a sucess, Exiting program..\n");
exit(0);
}
while(charactor!=EOF){
charactorBefore = charactor;
if (charactor==minorSeparatorChar)
flagMin=1;
charactor = fgetc(readFile);
if(charactorBefore == minorSeparatorChar){
flagMin = 0;
if (minSepCount==sequence[i]){
fputc(charactor,writeFile);
continue;
}
i++;
minSepCount++;
}
else if (charactorBefore == majorSeparatorChar){
minSepCount=0;
i=0;
majSepCount++;
fputc('\n',writeFile);
}
else{
if(flagMin==1)
fputc(charactor,writeFile);
continue;
}
}
fclose(readFile);
fclose(writeFile);
}
for example if the input file has
33|333|67|787|7889|9876554|56
20151001|0|0|0|0||94|71
1|94|71|1|94|71|1
and if I give sequence [2,5,6]
It should print to out file as
67 9876554 56
0 94 71
71 71 1
I ultimately concluded that there were too many flags and controls and variables in your code and that I couldn't make head or tail of what they were up to, and decided to rewrite the code. I couldn't see in your code how you knew how many fields were in the sequence, for example.
I write in C11 (C99), but in this program, that simply means that I declare variables when they're needed, not at the top of the function. If it's a problem (C89/C90), move the declarations to the top of the function.
I also find that the names used were so long that they obscured the purpose of the variables. You may think I've gone too far in the other direction; more significantly, your professor (teacher) may think that. So be it; names are fungible and global search and replace works well.
I also don't see how your code is supposed to interpolate semi-arbitrary numbers of blanks between the fields, so I've actually ducked the issue. This code outputs the field separator (minor_sep — a length reduction of minorSeparatorChar) and the record separator (major_sep — reduced from majorSeparatorChar) at the appropriate points.
I note that field numbers start with field 0 in your code. I'm not convinced your code would ever output data from field 0, but that is somewhat tangential given the rewrite.
I ended up with:
#include <stdio.h>
#include <stdlib.h>
static const int sequence[] = { 2, 5, 7 };
static const int seqlen = 3;
static
void getFormattedOutput(char *inFile, char *outFile, char minor_sep, char major_sep)
{
FILE *ifp = fopen(inFile, "r"); // opens the file for reading
FILE *ofp = fopen(outFile, "w"); // opens the file for writing
if (ifp == NULL || ofp == NULL)
{
printf("\nFile creation is not a success, Exiting program..\n");
exit(0);
}
int c;
int seqnum = 0;
int fieldnum = 0;
while ((c = getc(ifp)) != EOF)
{
if (c == major_sep)
{
putc(major_sep, ofp);
fieldnum = 0;
seqnum = 0;
}
else if (c == minor_sep)
{
if (seqnum < seqlen && fieldnum == sequence[seqnum])
{
putc(minor_sep, ofp);
seqnum++;
}
fieldnum++;
}
else if (fieldnum == sequence[seqnum])
fputc(c, ofp);
}
fclose(ifp);
fclose(ofp);
}
int main(void)
{
getFormattedOutput("/dev/stdin", "/dev/stdout", '|', '\n');
return 0;
}
When I run it (I called it split, though it isn't a good choice since there is also a standard command split), I get:
$ echo "fld0|fld1|fld2|fld3|fld4|fld5|fld6|fld7|fld8|fld9" | ./split
fld2|fld5|fld7|
$ echo "fld0|fld1|fld2|fld3|fld4|fld5|fld6" | ./split
fld2|fld5|
$
The only possible objection is that there is a field terminator rather than a field separator. As you can see, a terminator is not hard to implement; making it into a separator (so there isn't a pipe after the last field on the line, even when the line doesn't have as many fields as there are elements in the sequence — see the second sample output) is trickier. The code needs to output a separator when it reads the first character of a field that should be printed after the first such field. This code achieves that:
#include <stdio.h>
#include <stdlib.h>
static const int sequence[] = { 2, 5, 7 };
static const int seqlen = 3;
static
void getFormattedOutput(char *inFile, char *outFile, char minor_sep, char major_sep)
{
FILE *ifp = fopen(inFile, "r"); // opens the file for reading
FILE *ofp = fopen(outFile, "w"); // opens the file for writing
if (ifp == NULL || ofp == NULL)
{
printf("\nFile creation is not a success, Exiting program..\n");
exit(0);
}
int c;
int seqnum = 0;
int fieldnum = 0;
int sep = 0;
while ((c = getc(ifp)) != EOF)
{
if (c == major_sep)
{
putc(major_sep, ofp);
fieldnum = 0;
seqnum = 0;
sep = 0;
}
else if (c == minor_sep)
{
if (seqnum < seqlen && fieldnum == sequence[seqnum])
seqnum++;
fieldnum++;
sep = minor_sep;
}
else if (fieldnum == sequence[seqnum])
{
if (sep != 0)
{
putc(sep, ofp);
sep = 0;
}
putc(c, ofp);
}
}
fclose(ifp);
fclose(ofp);
}
int main(void)
{
getFormattedOutput("/dev/stdin", "/dev/stdout", '|', '\n');
return 0;
}
Example run:
$ {
> echo "Afld0|Afld1|Afld2|Afld3|Afld4|Afld5|Afld6|Afld7|Afld8|Afld9"
> echo "Bfld0|Bfld1|Bfld2|Bfld3|Bfld4|Bfld5|Bfld6|Bfld7|Bfld8|Bfld9"
> echo "Cfld0|Cfld1|Cfld2|Cfld3|Cfld4|Cfld5|Cfld6|Cfld7|Cfld8|Cfld9"
> echo "Dfld0|Dfld1|Dfld2|Dfld3|Dfld4|Dfld5|Dfld6|Dfld7|Dfld8|Dfld9"
> echo "Efld0|Efld1|Efld2|Efld3|Efld4|Efld5|Efld6|Efld7|Efld8|Efld9"
> } | ./split
|Afld2|Afld5|Afld7
|Bfld2|Bfld5|Bfld7
|Cfld2|Cfld5|Cfld7
|Dfld2|Dfld5|Dfld7
|Efld2|Efld5|Efld7
$