K&R(5.10): Command-line Arguments-find.c

/* k&r(5.10): Command-line Arguments
   created on Mar 23, 2011
   */
#include    "stdio.h"
#include    "string.h"
#define     MAXLINE 1000

int getline1(char *line, int max);

/* find: print lines that match pattern from 1st arg */
main(int argc, char *argv[])
{
    char line[MAXLINE];
    int found = 0;

    if (argc != 2)
      printf("Usage: find pattern\n");
    else
      while (getline1(line, MAXLINE) > 0)
        /* strstr(s,t): return a pointer to the first occurrence
           of the string t in the string s, or NULL if there is none. */
        if (strstr(line, argv[1]) != NULL) {
            printf("%s", line);
            found++;
        }
    return found;
}

/* find: print lines that match pattern from 1st arg,
improve version; find -n -x pattern, -n for print number of line; -x for except pattern. */
main(int argc, char *argv[])
{
    char line[MAXLINE];
    long lineno = 0;
    int c, except = 0, number = 0, found = 0;

    while (--argc > 0 && (*++argv)[0] == '-')
      while (c = *++argv[0]) //impcrements the pointer argv[0]
        switch (c) {
            case 'x':
                except = 1;
                break;
            case 'n':
                number = 1;
                break;
            default:
                printf("find: illegal option %c\n", c);
                argc = 0;
                found = -1;
                break;
        }

    if (argc != 1)
      printf("Usage: find -x -n pattern\n");
    else
      while (getline1(line, MAXLINE) > 0) {
        lineno++;
        /* strstr(s,t): return a pointer to the first occurrence
           of the string t in the string s, or NULL if there is none. */
        if ((strstr(line, *argv) != NULL) != except) {
            if (number)
              printf("%ld:", lineno);
            printf("%s", line);
            found++;
        }
}
return found;
}

/* getline: return the number of lines of input */
int getline1(char *line, int max)
{
    int i, c;
    i = 0;

    for (i = 0; i < max-1 && (c=getchar()) != EOF && c != '\n'; i++)
      line[i] = c;
    if (c = '\n')
      line[i++] = c;
    line[i] = '\0';
    return i;
}