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week1/task2.c

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+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * Week_1_Task_2
+ * Read in and reverse a string using recursion
+ */
+
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+
+void reverseR(char * str, int length);
+
+int main() {
+	char str[50];
+	printf("Enter a string: ");
+	scanf("%s", str);
+	reverseR(str, strlen(str));
+	printf("Result: %s\n", str);
+	return 0;
+}
+
+void reverseR(char *str, int length) {
+	/* check */
+	assert(length <= 50);
+	assert(length >= 0);
+
+	/* end of recursion */
+	if (length <= 1) {
+		return;
+	}
+
+	/* recursion */
+	char tmp;
+	tmp = str[0];
+	str[0] = str[length-1];
+	str[length-1] = tmp;
+
+	/* str move forward, length decrese 2 char */
+	reverseR(str+1, length-2);
+}