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How do get number line of file text on c ?. Help me .
Get sum number line.
I want read a file text.
EX:
for( line = 0; line < sumline; line ++) {
printf("char in line");
}
In case i understood the question :
#include <stdio.h>
#include <string.h>
main()
{
FILE *fp;
char * line;
size_t len = 0;
ssize_t read;
int lines = 0;
fp = fopen("input.txt", "r");
if( fp != NULL ){
while ((read = getline(&line, &len, fp)) != -1){
lines ++;
printf("%s\n", line);
}
fclose(fp);
}
printf("number of lines : %d\n", lines);
}
to count how many lines in your file
Try this:
`int lines = 0;
while ((read = getline(&line, &len, fp)) != -1) {
lines++;
}
cout << lines << endl;`
You can use the following function to get the number of lines inside a file.
#include <stdio.h>
// get the number of lines inside file
int getLineCnt(char *pcFileName) {
FILE *fp;
int lines=0;
fp = fopen(pcFileName, "r");
if(fp == NULL) { return -1; }
while (EOF != (fscanf(fp, "%*[^\n]"), fscanf(fp, "%*c"))) {
++lines;
}
io_fclose(fp);
return lines; ///\ retval number of lines
}
Related
I want to give input as line number and get output as the corresponding text for that line number in a text file.
Sample text file:
Hi this is Stefen
Hi How are you
Example input:
Enter the line number:2
Expected Output:
Hi How are you
My program is:
#include <stdio.h>
#include <stdlib.h>
int main() {
FILE *fp;
fp = fopen("sample.txt", "r");
if (fp == NULL) {
perror("Unable to open the file\n");
exit(1);
}
char buf[256];
while (fgets(buf, sizeof(buf), fp) != NULL) {
printf("%s\n", buf);
print("~~~~\n");
}
fclose(fp);
return 0;
}
Output I got:(The entire file with the separator ~~~~ below each line)
Hi this is Stefen
~~~~
Hi How are you
~~~~
Can anyone please tell me how to do this?
As pmg suggests, would you please try the following:
#include <stdio.h>
#include <stdlib.h>
#define INFILE "sample.txt"
int main()
{
FILE *fp;
char buf[BUFSIZ];
int count = 0, n;
fp = fopen(INFILE, "r");
if (fp == NULL) {
perror(INFILE);
exit(1);
}
printf("Enter the line number: ");
fgets(buf, sizeof buf, stdin);
n = (int)strtol(buf, (char **)NULL, 10);
while (fgets(buf, sizeof buf , fp) != NULL){
if (++count == n) {
printf("%s", buf);
break;
}
}
fclose(fp);
return EXIT_SUCCESS;
}
Best to use a second file
check if you're at \n that means new line and increment a variable like "line"
printf(" \n Enter line number of the line to be deleted:");
scanf("%d", &delete_line);
//open new file in write mode
ptr2 = fopen("c:\\CTEMP\\newfile.txt", "w");
if(ptr2==NULL)
printf("second error opening newfile");
while (!feof(ptr1))
{
ch = fgetc(ptr1);
if (ch == '\n')
{
temp++;
}
//except the line to be deleted
if (temp != delete_line)
{
//copy all lines in file newfile.c
fputc(ch, ptr2);
}
}
fclose(ptr1);
fclose(ptr2);
"detele_line" variable is for the user to inter.
The easiest way is using array to save the lines, then print the certain line.
#include <stdio.h>
#define M 10010
#define N 256
char buf[M][N];
int main(){
FILE *file;
char fileName[50] = "sample.txt";
file = fopen(fileName, "r");
if(file == NULL)
return 1;
int n = 0;
while(fgets(buf[n], N, file) != NULL){
n++;
}
fclose(file);
int i, x;
printf("Example input:\nEnter the line number:");
scanf("%d", &x);
printf("Expected Output:\n%s", buf[x-1]);
return 0;
}
This question already has answers here:
How can I read an input string of unknown length?
(11 answers)
Closed 3 years ago.
I have been trying to learn C, and was wondering: how would one get a string with an unknown length in C? I have found some results, but am not sure how to apply them.
If you're ok with extensions to the Standard, try POSIX getline().
Example from documentation:
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
FILE *fp;
char *line = NULL;
size_t len = 0;
ssize_t read;
fp = fopen("/etc/motd", "r");
if (fp == NULL)
exit(1);
while ((read = getline(&line, &len, fp)) != -1) {
printf("Retrieved line of length %zu :\n", read);
printf("%s", line);
}
if (ferror(fp)) {
/* handle error */
}
free(line);
fclose(fp);
return 0;
}
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I am working on a project. there is a .txt file that includes negative integers like this
0 -1 0
-1 20 -1
0 -1 0
My problem is I couldn't read negative numbers. What is your suggestions for this problem?
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(int argc, char * argv[]) {
FILE *fptr;
char letter;
fptr = fopen(argv[1],"r");
if(fptr == NULL){
printf("Please provide an argument\n");
exit(1);
}
while ( ( letter = fgetc(fptr) ) != EOF ) {
printf("%c",letter);
}
printf("\n");
fclose(fptr);
return 0;
}
You can try this to read the lines from the file and then parse your numbers.
getline reads a line from your file and strtok then gives you a string until the specified delimeter (space in your case). Hope this helps.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(int argc, char * argv[]) {
FILE * fptr = fopen(argv[1],"r");;
char * line = NULL;
size_t lineSize = 0;
if(fptr == NULL){
printf("Please provide an argument\n");
exit(1);
}
while(getline(&line, &lineSize, fptr) != -1) {
line[strcspn(line, "\n")] = 0;
printf("%s\n", line);
char * token = strtok(line, " ");
printf("%s\n", token);
while((token = strtok(NULL, " ")) != NULL) {
printf("%s\n", token);
}
}
fclose(fptr);
return 0;
}
Supposing that I have two files like this:
file1.txt
john
is
the new
guy
file2.txt
man
the old
is
rick
cat
dog
I'd like to compare first line from file1 with all the lines from file2 and verify if it exist. If not, go two the second line from file1 and compare it with all the lines from file2.. and so on until eof is reached by file1.
The output that I expect is:
john
the new
guy
How I thought this should be done:
read file1 and file2
create a function which returns the line number of each of them
take the first line from file1 and compare it to all the lines from file2
do this until all the lines from file1 are wasted
Now, I don't know what I'm doing wrong, but I don't get the result that I expect:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int countlines(char *filename)
{
int ch = 0, lines = 0;
FILE *fp = fopen(filename, "r");
if (fp == NULL)
return 0;
do {
ch = fgetc(fp);
if (ch == '\n')
lines++;
} while (ch != EOF);
if (ch != '\n' && lines != 0)
lines++;
fclose(fp);
return lines;
}
int main(int argc, char *argv[])
{
FILE *template_file = fopen(argv[1], "r");
FILE *data_file = fopen(argv[2], "r");
char buffer_line_template_file[100];
char buffer_line_data_file[100];
if (argc != 3)
{
perror("You didn't insert all the arguments!\n\n");
exit(EXIT_FAILURE);
}
if (template_file == NULL || data_file == NULL)
{
perror("Error while opening the file!\n\n");
exit(EXIT_FAILURE);
}
int counter = 0;
for (int i = 0; i < countlines(argv[1]); i++)
{
fgets(buffer_line_template_file, 100, template_file);
for (int j = 0; j < countlines(argv[2]); j++)
{
fgets(buffer_line_data_file, 100, data_file);
if (strcmp(buffer_line_template_file, buffer_line_data_file) != 0)
{
counter++;
printf("%d", counter);
}
}
}
printf("\n\n");
return 0;
}
Could someone please point me into the right direction ? For testing purposes I created a counter at the end which was a part of a small debug. There should be the print() function
As per #chux answer I got the following simplified code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
FILE *template_file = fopen(argv[1], "r");
FILE *data_file = fopen(argv[2], "r");
char buffer_line_template_file[100];
char buffer_line_data_file[100];
if (argc != 3)
{
perror("You didn't insert all the arguments!\n\n");
exit(EXIT_FAILURE);
}
if (template_file == NULL || data_file == NULL)
{
perror("Error while opening the file!\n\n");
exit(EXIT_FAILURE);
}
while(fgets(buffer_line_template_file, 100, template_file))
{
buffer_line_template_file[strcspn(buffer_line_template_file, "\n")] = '\0';
rewind(data_file);
while (fgets(buffer_line_data_file, 100, data_file))
{
buffer_line_data_file[strcspn(buffer_line_data_file, "\n")] = '\0';
if (strcmp(buffer_line_template_file, buffer_line_data_file) != 0)
{
printf("%s\n", buffer_line_template_file);
}
}
}
printf("\n\n");
return 0;
}
The above code is giving me the following output, which is not what is expected:
john
john
john
john
john
john
is
is
is
is
is
the new
the new
the new
the new
the new
the new
guy
guy
guy
guy
guy
guy
Problems with OP's code
Imprecise definition of line.
Excessive recalculation
Fuzzy determination of the number of lines in a file.
Unlike string, which has a precise definition in C, reading a line is not so well defined. The primary specificity issue: does a line contain the trailing '\n'. If the first answer is Yes, then does the last text in a file after a '\n' constitute a line? (Excessively long lines are another issue, but let us not deal with that today.)
Thus possibly some lines end with '\n' and others do not, fooling strcmp("dog", "dog\n").
The easiest solution is to read a line until either 1) a '\n' is encountered, 2) EOF occurs or 3) line buffer is full. Then after getting a line, lop off the potential trailing '\n'.
Now all lines code subsequently works with have no '\n'.
fgets(buffer_line_template_file, 100, template_file);
buffer_line_template_file[strcspn(buffer_line_template_file, "\n")] = '\0';
OP's loop is incredible wasteful. Consider a file with 1000 lines. Code will loop, calling 1000 times countlines() (each countlines() call reads 1000 lines) times when one countlines() call would suffice.
// for (int j = 0; j < countlines(argv[2]); j++)
int j_limit = countlines(argv[2]);
for (int j = 0; j < j_limit; j++)
There really is no need to count the line anyways, just continue until EOF (fgets() returns NULL). So no need to fix its fuzzy definition. (fuzzy-ness concerns same issues as #1)
int counter = 0;
for (fgets(buffer_line_template_file, 100, template_file)) {
buffer_line_template_file[strcspn(buffer_line_template_file, "\n")] = '\0';
rewind(data_file);
while ((fgets(buffer_line_data_file, 100, data_file)) {
buffer_line_data_file[strcspn(buffer_line_data_file, "\n")] = '\0';
if (strcmp(buffer_line_template_file, buffer_line_data_file) != 0) {
counter++;
printf("%d", counter);
}
}
}
Other simplifications possible - for another day.
FWIW, following counts lines of text allowing the last line in the file to optionally end with a '\n'.
unsigned long long FileLineCount(FILE *istream) {
unsigned long long LineCount = 0;
rewind(istream);
int previous = '\n';
int ch;
while ((ch = fgetc(inf)) != EOF) {
if (previous == '\n') LineCount++;
previous = ch;
}
return LineCount;
}
Note that this function may get a different result that fgets() calls. Consider a file of one line of 150 characters. fgets(..., 100,...) will report 2 lines. FileLineCount() reports 1.
[Edit] Updated code to conform to OP functionality.
int found = 0;
while (fgets(buffer_line_data_file, 100, data_file))
{
buffer_line_data_file[strcspn(buffer_line_data_file, "\n")] = '\0';
if (strcmp(buffer_line_template_file, buffer_line_data_file) == 0)
{
found = 1;
break;
}
}
if (!found) printf("%s\n", buffer_line_template_file);
This program prints the diff of two files file1.txt and file2.txt.
#include<stdio.h>
#include <stdlib.h>
#include <memory.h>
int main() {
FILE *fp1, *fp2;
int ch1, ch2;
char fname1[40], fname2[40];
char *line = NULL;
size_t len = 0;
ssize_t read;
char *line2 = NULL;
size_t len2 = 0;
ssize_t read2;
fp1 = fopen("file1.txt", "r");
fp2 = fopen("file2.txt", "r");
if (fp1 == NULL) {
printf("Cannot open %s for reading ", fname1);
exit(1);
} else if (fp2 == NULL) {
printf("Cannot open %s for reading ", fname2);
exit(1);
} else {
while ((read = getline(&line, &len, fp1)) != -1 && (read2 = getline(&line2, &len2, fp2)) != -1) {
if (!strcmp(line, line2)) {
printf("Retrieved diff on line %zu :\n", read);
printf("%s", line);
}
}
if (ch1 == ch2)
printf("Files are identical \n");
else if (ch1 != ch2)
printf("Files are Not identical \n");
fclose(fp1);
fclose(fp2);
}
return (0);
}
You already have a very good answer (and always will from chux), but here is a slightly different approach to the problem. It uses automatic storage to reading file2 into an array of strings and then compares each line in file1 against every line in file2 to determine whether it is unique. You can easily convert the code to dynamically allocate memory, but for sake of complexity that was omitted:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
enum { MAXC = 256, MAXL = 512 };
void file1infile2 (FILE *fp2, FILE *fp1, size_t *n2, size_t *n1);
int main (int argc, char **argv) {
FILE *fp1 = fopen (argc > 1 ? argv[1] : "file1.txt", "r");
FILE *fp2 = fopen (argc > 2 ? argv[2] : "file2.txt", "r");
size_t n1 = 0, n2 = 0;
if (!fp1 || !fp2) {
fprintf (stderr, "error: file open failed.\n");
return 1;
}
printf ("\nunique words in file1, not in file 2.\n\n");
file1infile2 (fp2, fp1, &n2, &n1);
printf ("\nanalyzed %zu lines in file1 against %zu lines in file2.\n\n",
n1, n2);
return 0;
}
void file1infile2 (FILE *fp2, FILE *fp1, size_t *n2, size_t *n1)
{
char buf[MAXC] = "";
char f2buf[MAXL][MAXC] = { "" };
size_t i;
*n1 = *n2 = 0;
while (*n2 < MAXL && fgets (buf, MAXC, fp2)) {
char *np = 0;
if (!(np = strchr (buf, '\n'))) {
fprintf (stderr, "error: line exceeds MAXC chars.\n");
exit (EXIT_FAILURE);
}
*np = 0;
strcpy (f2buf[(*n2)++], buf);
}
while (*n1 < MAXL && fgets (buf, MAXC, fp1)) {
char *np = 0;
if (!(np = strchr (buf, '\n'))) {
fprintf (stderr, "error: line exceeds MAXC chars.\n");
exit (EXIT_FAILURE);
}
*np = 0, (*n1)++;
for (i = 0; i < *n2; i++)
if (!(strcmp (f2buf[i], buf)))
goto matched;
printf (" %s\n", buf);
matched:;
}
}
Look over the code and let me know if you have any questions.
Example Use/Output
$ ./bin/f1inf2 dat/f1 dat/f2
unique words in file1, not in file 2.
john
the new
guy
analyzed 4 lines in file1 against 6 lines in file2.
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Given the following snippet, fin containing random text with data always following a command:
#define COMMANDSIZE 16
#define DATASIZE 128
int i, j, k, ch;
char command[COMMANDSIZE];
char data[DATASIZE];
FILE* fin;
FILE* fout;
fin = fopen("input.txt", "r");
fout = fopen("output.txt", "w");
fseek(fout, 0, SEEK_SET);
while ((ch = fgetc(fin)) != EOF)
{
for (i = 0; i < sizeof(command); i++) //obtain command from input stream
{
command[i] = fgetc(fin) & 0xff;
}
for (j = 0; j < sizeof(data); j++) //obtain data from input stream
{
data[j] = fgetc(fin) & 0xff;
}
for (k = 0; k < sizeof(data); k++) //write data to output stream
{
fseek(fout, /* computed block address */, SEEK_CUR);
fputc(data[k], fout);
}
}
fclose(fout);
fclose(fin);
Comparing the input and output file, some data in the input file did not carry over. Thus, I tried doing the above with while(1), and again, some data in the input file did not carry over, but it wasn't the same data as using while((ch = fgetc(fin)) != EOF), and there was not an intersect (some overlap) between the different output files.
How can I ensure all data from the input file is written to the output file? Does this have to do with fgetc() and/or fputc()?
A few things are not clear to me here.
while ((ch = fgetc(fin)) != EOF)
Do you intend to throw away the character you just read?
fseek(fout, 1, SEEK_CUR);
Why are you skipping ahead one byte? Writing will advance the file automatically. I don't think you want to advance the file position twice.
I would do something like this instead:
char command[COMMANDSIZE];
char data[DATASIZE];
FILE* fin;
FILE* fout;
fin = fopen("input.txt", "rb");
fout = fopen("output.txt", "wb");
while (fread(command, sizeof(command), 1, fin) != EOF)
{
if (fread(data, sizeof(data), 1, fin) != EOF)
{
fseek(...); /* Seek to the block where current data should be written */
fwrite(data, sizeof(data), 1, fout);
}
}