Solve exercise 1.19: Reverse each line of input

1 files changed, 54 insertions, 0 deletions

diff --git a/1-19_reverse-lines.c b/1-19_reverse-lines.c
new file mode 100644
index 0000000..d87b625
--- /dev/null
+++ b/1-19_reverse-lines.c
@@ -0,0 +1,54 @@
+#include <stdio.h>
+
+#define MAXLINELENGTH 9001
+
+int get_line(char s[], int limit) {
+	int c, i;
+
+	for (i = 0; i < limit && (c = getchar()) != EOF && c != '\n'; ++i) {
+		s[i] = c;
+	}
+
+	s[i] = '\0';
+
+	/* If I don't include this check, I can't handle blank lines */
+	if (c == EOF && i == 0) {
+		return -1;
+	} else {
+		return i;
+	}
+
+}
+
+/* Directly reverse a line's contents. */
+void reverse(char input[], int size) {
+	int tmp;
+	int i = 0;
+	size--;
+
+	/* If len and i are the same, then there's no reason to proceed */
+	while (size > i) {
+		// Store the first character in a temporary spot...
+		tmp = input[i];
+
+		// ... and swap!
+		input[i] = input[size];
+		input[size] = tmp;
+
+		// Bring our numbers closer together
+		++i;
+		--size;
+	}
+}
+
+int main(void) {
+	// An int and a string to store each line's data in
+	int line_len;
+	char buffer[MAXLINELENGTH];
+
+	while ((line_len = get_line(buffer, MAXLINELENGTH)) != -1) {
+		reverse(buffer, line_len);
+		printf("%s\n", buffer);
+	}
+	return 0;
+}