1 files changed, 58 insertions, 0 deletions
diff --git a/four/grep.c b/four/grep.c
new file mode 100644
index 0000000..7e6b4db
--- /dev/null
+++ b/four/grep.c
@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <string.h>
+
+#define MAXLINE 1024
+
+int
+get_line(char s[], int lim)
+{
+	int c, i;
+	i = 0;
+	while (--lim > 0 && (c = getchar()) != EOF && c != '\n') {
+		s[i++] = c;
+	}
+	if (c == '\n') {
+		s[i++] = c;
+	}
+	s[i] = '\0';
+	return i;
+}
+
+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;
+}
+
+int strrindex(char s[], char t[])
+{
+	int i, j, k;
+	for (i = strlen(s) - 1; i > 0; --i) {
+		for (j = i, k = strlen(t) - 1; k > 0 && s[j] == t[k]; --j, --k);
+		if (t[k] == t[0]) {
+			return i;
+		}
+	}
+	return -1;
+}
+
+int
+main()
+{
+	char line[MAXLINE];
+	char pattern[] = "ould";
+	int found = 0;
+	while (get_line(line, MAXLINE)) {
+		if (strrindex(line, pattern) >= 0) {
+			printf("%s", line);
+			++found;
+		}
+	}
+	return found;
+}