Hello guys i have an external file like this :
I want to read all character (include space and new line) to my 2-Dimensional(row and column) array, but i failed to do that. Example, in that file at line 10 and column 1 (the bottom left corner) there is a '/' character. I want to put '/' in my array[9][0] (index in array start from 0 not 1), so every character is located in array as same as the file.
Here is my code :
#include <stdio.h>
int main(void) {
/** my index array variable, i for row and j for column */
int i;
int j;
/** varible to read character */
char c;
/** array for the input. The file will not consist more than 17 rows and 2017 columns*/
char input[17][2017];
/** pointer to a file */
FILE *fp;
/** read that file. (my code and that file are located in the same place) */
fp = fopen("bangun.in", "r");
/** start reading the file */
i = 0;
j = 0;
while ( (c = fgetc(fp)) != EOF){
if (c != 0) {
input[i][j]=c;
}
else if (c == '\n') {
input[i][j]=c;
printf("get in");
i++;
}
j++;
}
fclose(fp);
return 0;
}
if my algoritm is worng, could you tell me how to it? my aim is copy all character with the position into my array.
Your if logic is wrong, if c == 0 (else condition) it will never be a new line.
Related
I'm trying to do some simple tasks in C and run them from the command line in Linux.
I'm having some problems with both C and running the code from the command line with a given filename given as a parameter. I've never written code in C before.
Remove the even numbers from a file. The file name is transferred to
the program as a parameter in the command line. The program changes
this file.
How do I do these?
read from a file and write the results over the same file
read numbers and not digits from the file (ex: I need to be able to read "22" as a single input, not two separate chars containing "2")
give the filename through a parameter in Linux. (ex: ./main.c file.txt)
my attempt at writing the c code:
#include <stdio.h>
int main ()
{
FILE *f = fopen ("arr.txt", "r");
char c = getc (f);
int count = 0;
int arr[20];
while (c != EOF)
{
if(c % 2 != 0){
arr[count] = c;
count = count + 1;
}
c = getc (f);
}
for (int i=0; i<count; i++){
putchar(arr[i]);
}
fclose (f);
getchar ();
return 0;
}
Here's a complete program which meets your requirements:
write the results over the same file - It keeps a read and write position in the file and copies characters towards the file beginning in case numbers have been removed; at the end, the now shorter file has to be truncated. (Note that with large files, it will be more efficient to write to a second file.)
read numbers and not digits from the file - It is not necessary to read whole numbers, it suffices to store the write start position of a number (this can be done at every non-digit) and the parity of the last digit.
give the filename through a parameter - If you define int main(int argc, char *argv[]), the first parameter is in argv[1] if argc is at least 2.
#include <stdio.h>
#include <ctype.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
if (argc < 2) return 1; // no argument given
FILE *f = fopen(argv[1], "rb+");
if (!f) return 1; // if fopen failed
// read, write and number position
long rpos = 0, wpos = 0, npos = 0;
int even = 0, c; // int to hold EOF
while (c = getc(f), c != EOF)
{
if (isdigit(c)) even = c%2 == 0;
else
{
if (even) wpos = npos, even = 0;
npos = wpos+1; // next may be number
}
fseek(f, wpos++, SEEK_SET);
putc(c, f);
fseek(f, ++rpos, SEEK_SET);
}
ftruncate(fileno(f), wpos); // shorten the file
}
I'd do that like this (removing extra declarations => micro optimizations)
/**
* Check if file is avaiable.
*/
if (f == NULL)
{
printf("File is not available \n");
}
else
{
/**
* Populate array with even numbers.
*/
while ((ch = fgetc(f)) != EOF)
ch % 2 != 0 ? push(arr, ch); : continue;
/**
* Write to file those numbers.
*/
for (int i = 0; i < 20; i++)
fprintf(f, "%s", arr[i]);
}
Push implementation:
void push(int el, int **arr)
{
int *arr_temp = *arr;
*arr = NULL;
*arr = (int*) malloc(sizeof(int)*(n - 1));
(*arr)[0] = el;
for(int i = 0; i < (int)n - 1; i++)
{
(*arr)[i + 1] = arr_temp[i];
}
}
In order to write to the same file, without closing and opening it, you should provide both methods, w+ (writing and reading), and this method will clear it's content.
So, change the line where you open the file, for this.
FILE *f = fopen ("arr.txt", "w+");
You should look for ways of implementing dynamic arrays (pointers and memory management).
With this example you could simply go ahead and write yourself, inside the main loop, a temporary variable that stores a sequence of numbers, and stack those values
Something like this (pseudocode, have fun :)):
DELIMITER one of (',' | '|' | '.' | etc);
char[] temp;
if(ch not DELIMITER)
push ch on temp;
else
push temp to arr and clear it's content;
Hope this was useful.
I am stuck at a C language problem in which I was supposed to input name and age of players from their respective files and output the same for a specific number of players which will be taken input (OR -1 to exit). The problem has to be solved using structures. I have attached the output I am getting along with the data that the age and name files contained.
Can someone explain to me where I am doing wrong?
Any help in optimisation too will be really helpful. Thanks!
Following is the code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct Cricket_Player_DataBase
{
char name[30];
int score;
char role[11];
int age;
int wickets;
};
int main()
{
FILE *nf_ptr , *af_ptr; //nf_ptr is pointing to name.txt file | af_ptr is pointing to age.txt file
nf_ptr = fopen("name.txt","r");
af_ptr = fopen("age.txt","r");
int number_of_players = 0; //will be used to fix the size of array of structures
// following code is used just to count number of players, upto the point where 'HERE' is written
int temp, border_check = 0;
while((temp = fgetc(af_ptr)) != EOF)
{
if(temp == '\n')
{
++number_of_players;
border_check = 0;
}
else border_check++;
}
if(border_check > 0) ++number_of_players;
af_ptr = fopen("age.txt","r");
// HERE
struct Cricket_Player_DataBase players[number_of_players];
int temp_age , zero = 0 ;
char temp_char[30] , ch ;
for(int i=0; i < number_of_players; ++i)
{
temp_age = fgetc(af_ptr);
players[i].age = temp_age;
while((ch = fgetc(nf_ptr)) != EOF)
{
if(ch == '\n')
{
strncpy(players[i].name , temp_char , zero+1);
zero = 0;
break;
}
else
{
temp_char[zero] = ch;
zero++;
}
}
}
int input;
printf("Enter number of players you want to see the data of OR type -1 to exit : ");
scanf("%d", &input);
if(input > 0)
{
for(int i = 0; i < input; ++i)
{
printf("Data of player #%d is \nName : %s\nAge : %d\n", i+1 , players[i].name , players[i].age);
}
}
fclose(nf_ptr);
fclose(af_ptr);
return 0;
}
Output I got.
Name file was this.
Age file was this.
You're opening af_ptr without closing it. It could cause problems. If you want to open the same file again, use function rewind(file) or fclose it and open it again.
This is because you have made an assumption that the end of each name and age in your text files is a line feed character '\n'. Assuming you have created your text files in a windows machine, the line endings are \r\n, that is - a carriage return character followed by a line feed. Using Hex Editor Neo, here's what your files' contents would look like.
Your name.txt file
Your age.txt file
Notice the line endings - '0x0d' is a carriage return '\r' and '0x0a' is a line feed '\n'. Modify your program to take this into account.
Read more about line endings here: https://blog.codinghorror.com/the-great-newline-schism/
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
$
I am sorry the question was not very clear and the code i have so far is shown below and i am just stuck on how i can use the while loop to print the contents of the file.
#include<stdio.h>
int main()
{
FILE *number;
/* Open the file 'numbers' for reading */
number = fopen("numbers.dat", "r");
if (number != NULL) {
/* A bit of space for a line of text */
char lineOfText[100];
while (fgetc(lineOfText, 100, number) != NULL) {
printf("%s\n", lineOfText);
}
fclose(number);
}
/* sorry, my question was not clear and to clarify i am trying to
Print out the contents of the file with one entry per line, my .dat file includes
1,2,3,4,5,6,7,8,9 and i am trying to print them out in this format
1
2
3
4 and so on...
*/
To start you off...
FILE * f;
int c;
f=fopen ("numbers.txt","r");
while((c = fgetc(f)) != EOF) printf("%c", isdigit(c)? c : ' ');
fclose (f);
The code is supposed to read a user-inputted text file name, copy every character into a multidimensional array, then display it with standard output. It compiles, but produces unintelligible text. Am I missing something?
for (i = 0; i < BIGGEST; i++) {
for (j = 0; j < BIGGESTL; j++) {
if (fgetc(array, fp) ) != EOF)
array[i][j] = c;
else array[i][j] = '\0'
}
fclose(fp);
return 0;
}
You stop filling the array when you encounter EOF, but you print the full array out no matter what.
If the data read from the file is smaller than the input array, you will read that data in and then print that data out, plus whatever random characters were in the memory locations that you do not overwrite with data from the file.
Since the requirement seems to be to print text data, you could insert a special marker in the array (e.g. '\0') to indicate the position where you encountered EOF, and stop displaying data when you reach that marker.
You had better read each line from file
For example:
int i = 0;
while(fgets(text[i],1000,fp))
{
i++;
}
Though the question is edited and only part of the code is left in question. I am posting more than what is required for the question at the moment.
Reason being, there can be numberous improvements to originally posted full code.
In main() function:
You need to check for the argc value to be equal to 2 for your purpose and only then read in value of argv[1] . Else if program executed without the command-line-argument which is file_name in this case, invalid memory read occurs, resulting in segmentation fault if you read in argv[1].
In read_file_and_show_the contents() function:
Stop reading file if end of file is reached or maximum characters is read and store in the character array.
Below Program will help you visualize:
#include <stdio.h>
/*Max number of characters to be read/write from file*/
#define MAX_CHAR_FOR_FILE_OPERATION 1000000
int read_and_show_the_file(char *filename)
{
FILE *fp;
char text[MAX_CHAR_FOR_FILE_OPERATION];
int i;
fp = fopen(filename, "r");
if(fp == NULL)
{
printf("File Pointer is invalid\n");
return -1;
}
//Ensure array write starts from beginning
i = 0;
//Read over file contents until either EOF is reached or maximum characters is read and store in character array
while( (fgets(&text[i++],sizeof(char)+1,fp) != NULL) && (i<MAX_CHAR_FOR_FILE_OPERATION) ) ;
//Ensure array read starts from beginning
i = 0;
while((text[i] != '\0') && (i<MAX_CHAR_FOR_FILE_OPERATION) )
{
printf("%c",text[i++]);
}
fclose(fp);
return 0;
}
int main(int argc, char *argv[])
{
if(argc != 2)
{
printf("Execute the program along with file name to be read and printed. \n\
\rFormat : \"%s <file-name>\"\n",argv[0]);
return -1;
}
char *filename = argv[1];
if( (read_and_show_the_file(filename)) == 0)
{
printf("File Read and Print to stdout is successful\n");
}
return 0;
}