Reading one line at a time in C
Use the following program for getting the line by line from a file.
#include <stdio.h>
int main ( void )
{
char filename[] = "file.txt";
FILE *file = fopen ( filename, "r" );
if (file != NULL) {
char line [1000];
while(fgets(line,sizeof line,file)!= NULL) /* read a line from a file */ {
fprintf(stdout,"%s",line); //print the file contents on stdout.
}
fclose(file);
}
else {
perror(filename); //print the error message on stderr.
}
return 0;
}
This should work, when you can't use fgets()
for some reason.
int readline(FILE *f, char *buffer, size_t len)
{
char c;
int i;
memset(buffer, 0, len);
for (i = 0; i < len; i++)
{
int c = fgetc(f);
if (!feof(f))
{
if (c == '\r')
buffer[i] = 0;
else if (c == '\n')
{
buffer[i] = 0;
return i+1;
}
else
buffer[i] = c;
}
else
{
//fprintf(stderr, "read_line(): recv returned %d\n", c);
return -1;
}
}
return -1;
}
If you are coding for a platform that has the GNU C library available, you can use getline():
http://www.gnu.org/s/libc/manual/html_node/Line-Input.html
The fgets
function will read a single line from a file or num
characters where num
is the second parameter passed to fgets
. Are you passing a big enough number to read the line?
For Example
// Reads 500 characters or 1 line, whichever is shorter
char c[500];
fgets(c, 500, pFile);
Vs.
// Reads at most 1 character
char c;
fgets(&c,1,pFile);
This is more of a comment than a complete answer, but I don't have enough points to comment. :)
Here's the function prototype for fgets():
char *fgets(char *restrict s, int n, FILE *restrict stream);
It will read n-1 bytes or up to a newline or eof. For more info see here