How to read a specific amount of lines from a file in C - c

Question

My question is that I am trying to read only a certain amount of files given n files.
For example, I have the two files with the following content inside then
test1:
A cat ran off
Apple
test2:
The boy went home
Apples are red
I want the output to be
test1: A cat ran off
Not
test1: A cat ran off
test2: Apples are red
This is the code that I have written so far:
#include <stdio.h>
#include <string.h>
int main (int argc, char ** argv)
{
extern int searcher(char * name, char*search,int amount);
while(argc != 0){
if(argv[argc] !=NULL)
if(searcher(argv[argc],"a",1)) break;
argc-- ;
}
}
int searcher(char * name, char*search,int amount){
FILE *file = fopen (name, "r" );
int count = 0;
if (file != NULL) {
char line [1000];
while(fgets(line,sizeof line,file)!= NULL && count != amount)
{
if(strstr(line,search) !=NULL){
count++;
if(count == amount){
return(count);
}
printf("%s:%s\n", line,name);
}
}
fclose(file);
}else {
perror(name); //print the error message on stderr.
}
return(0);
}

Answer 1

Continuing from the comments, and noting you will need to remove the trailing newline included by fgets, you could do something like the following:
#include <stdio.h>
#include <string.h>
enum { MAXC = 1000 };
int searcher (char *name, char *search, int amount);
void rmlf (char *s);
int main (int argc, char **argv)
{
int i;
for (i = 1; i < argc; i++)
if (searcher (argv[i], "a", 1))
break;
return 0;
}
int searcher (char *name, char *search, int amount)
{
FILE *file = fopen (name, "r");
int count = 0;
if (!file) {
fprintf (stderr, "error: file open failed '%s'.\n", name);
return 0;
}
char line[MAXC] = "";
while (count < amount && fgets (line, MAXC, file)) {
rmlf (line); /* strip trailing \n from line */
if (strstr (line, search)) {
count++;
printf ("%s: %s\n", name, line);
}
}
fclose (file);
return count == amount ? count : 0;
}
/** stip trailing newlines and carraige returns by overwriting with
* null-terminating char. str is modified in place.
*/
void rmlf (char *s)
{
if (!s || !*s) return;
for (; *s && *s != '\n'; s++) {}
*s = 0;
}
Example Input Files
$ cat test1
A cat ran off
Apple
$ cat test2
The boy went home
Apples are red
Example Use/Output
You understand iterating with argc-- your files are processed in reverse, so you will end up with output like:
$ ./bin/searcher test2 test1
test1: A cat ran off
$ ./bin/searcher test1 test2
test2: Apples are red
note: to process the files in order, just do something like for (i = 1; i < argc; i++) instead of while (argc--). Let me know if you have further questions.
Changing to the for loop instead of the while in main and inputting 10 as the number of occurrences to look for, all files are processed, e.g.:
$ ./bin/searcher test1 test2
test1: A cat ran off
test2: Apples are red