Code:#include <stdio.h> #include <stdlib.h> #include <string.h> int main( int argc, char **argv) { char *input = argv[0]; FILE *fp; if ( (fp = fopen(input,"r")) == 0 ){printf("open '%s' error.\n",input); exit(0);} int i = 0; while( feof(fp) == 0 ) { char buf[100]; fgets(buf,100,fp); if ( strlen(buf) >= 2 ) ++i; printf("%s\n",buf); } printf("line number:%d\n",i); return 0; }
You should give us more info.
Question 12.2
Don't use feof() to control loop condition.
Originally Posted by Bayint Naung
get wrong line number, why?Code:while( fgets(buf,100,fp) != NULL ) { //char *x = fgets(buf,100,fp); i++; printf("%s\n",buf); //fputs(buf, fp); } printf("line number:%d\n",i);
Last edited by zcrself; 10-14-2010 at 12:50 AM.
Each line ends with newline.
So count the newlines.
Extrapolate line numbers from this information.
What do you mean by 'can't get line number'?!
Is it giving you wrong line number or what???
Yes.
Can attach your text file? and post output of your program.
program:
input:Code:#include <stdio.h> #include <stdlib.h> #include <string.h> int getLineCount(char *input) { FILE *fp;int i = 0; char buf[100]; memset(buf,0x00,sizeof(buf)); if ( (fp = fopen(input,"r")) == 0 ){printf("open '%s' error.\n",input); exit(0);} while( fgets(buf,44,fp) != NULL ) { i++; //printf("%d %s\n",i,buf); } return i; } int main( int argc, char **argv) { char *input = argv[0]; printf("line number:%d\n",getLineCount(input)); return 0; }
output:Code:@HWI-EAS-249_38:2:1:2:857.R AAAGTATGTAGGACTCATGNNNNTNNNNNNNCNNNNNNAN + ?8BBBBBBBBBB;BB<'<,'''';'''''''9'''''','
Code:line number:180
Last edited by zcrself; 10-14-2010 at 02:08 AM.
> get wrong line number, why?
Unless you know FOR SURE that every line is <98 characters in length, then you're going to end up counting the number of lines AND the number of 99-character blocks that make up long lines.
Make sure buf contains a \n before incrementing.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
I can't understand your answer clearly
I would declare char buff[] at the top of the function, and NOT inside the while loop.
Salem is saying that, if your input file has any line longer than the buffer, the line count will be incorrect. That's because of the way fgets() works when it encounters long lines.
Read the documentation for more information on how fgets() works.
Furthermore, if you have an input file with non-text characters, you may get different results too (although counting lines in such a file is rather an academic exercise).
