C PROGRAM FOR GREP

#include
#include
#define BUFSIZE 256
#define FAILURE -1
#define SUCCESS 0
int
main(int argc, char *argv[])
{
void search_pattern(char *buf, char *pattern);
char buf[BUFSIZE];
char pattern[BUFSIZE];
char file_name[BUFSIZE];
FILE *fp;
/*get the command line arguments into local variables */
memset(pattern, 0, BUFSIZE);
memset(buf, 0, BUFSIZE);
memset(file_name, 0, BUFSIZE);
strcpy(pattern, argv[1]);
strcpy(file_name, argv[2]);
/* open the file in read mode */
fp=(FILE *)fopen(file_name, "r");
if(fp==NULL)
{
/* return in case of failure */
perror("fopen():");
return FAILURE;
}
/* read one line from the file till end of file is reached */
while(fgets(buf, BUFSIZE, fp)!=NULL)
{
search_pattern(buf, pattern);
}
fclose(fp);
return SUCCESS;
}
void
search_pattern(char *buf, char *pattern)
{
char *p, *q;
for(p=buf, q=pattern; *p!='\0'; p++)
{
if(*p != *q)
continue;
else
{
for( ; *p==*q; p++, q++);
if(*q=='\0')
{
/* pattern found. print it */
printf("%s\n", buf);
return;
}
q=pattern;
}
}
getch();
}