K&R(4.1): Basics of Functions

/* k&r(4.1): Basic of Functions
   created on Mar 21, 2011
 */

# include <stdio.h>
# include <string.h>
/* analysis: the job fall neatly into three pieces:
   * while (there's another line)
          if (the line contains the pattern)
              print it
*/
#define MAXLINE 1000 /* maximum input line length */
int mgetline(char line[], int max);
int strindex(char source[], char searchfor[]);

/* main: print each line of its input that contains a pattern */
int main()
{
    char line[MAXLINE];
    int found = 0;
    printf("The length of line is %d\n", strlen(line));
    char pattern[] = "ould"; /* pattern to search for */
    while (mgetline(line, MAXLINE) > 0 )
      if (strindex(line, pattern) >= 0) {
          printf("%s", line);
          found++;
    }

    return found;
}

/* getline: get line into s, return length */
int mgetline(char s[], int lim)
{
    int c, i;

    i = 0;
    /* or use while like this:
     *   while (--lim > 0 && (c=getchar()) != EOF && c != '\n')
               s[i++] = c;
      */
    for (i = 0; (c = getchar()) != EOF &&  '\n'; ++i)
      s[i] = c;

    if (c == '\n')
      s[i++] = c;
    s[i] = '\0';
    return i;
}

/* strindex: return index of t in s, -1 if none */
int strindex(char s[], char t[])
{
    int i, j, k;

    for (i = 0; s[i] != '\0'; i++) {
        for (j = i, k = 0; t[k]!='\0' && s[j] == t[k]; j++, k++)
          ;
        if (k > 0 && t[k] == '\0')
          return i;
    }
    return -1;
}