add Exercise 3: Reverse Temperature Converter for Chapter 1.3 (danwri…

…tecode#144) danwritecode#154

exercises/03_for_statement/README.md

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+For more information please refer to Chapter 1.3 of "The C Programming Language".

exercises/03_for_statement/for_statement_01.c

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+/** LEARNING
+ * Your goal is to understand how the for statement works.
+ *
+ * The for statement has the following syntax:
+ *
+ * for (initialization; condition; increment) {
+ *		statement;
+ * 	 	statement;
+ * 	 	...
+ * }
+ *
+ * The for statement is equivalent to the following while statement:
+ *
+ * initialization;
+ * while (condition) {
+ *		statement;
+ * 		statement;
+ * 		...
+ *		increment;
+ *	}
+ */
+
+/** EXERCISE
+ * Your job is to write a for statement equivalent to the following 
+ * while statement:
+ *
+ * i = 0; // initialization
+ * while (i < 10) { // condition
+ *	printf("%d\n", i);
+ *	verify_count(&count, i);
+ *	i++; // increment
+ * }
+ */
+
+// ❌ I AM NOT DONE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+
+// DO NOT CHANGE THIS
+static int track = 0, count = 0;
+
+// DO NOT CHANGE THIS
+void verify_count (int *count, int i) {
+	assert(i == track++);
+	(*count)++;
+}
+
+int main() {
+	int i = rand() % 100 + 11; // DO NOT CHANGE THIS
+
+	// YOUR CODE HERE
+	for (initialization; condition; increment) {
+	// END YOUR CODE
+		printf("%d\n", i);
+		verify_count(&count, i); // DO NOT CHANGE THIS
+	}
+
+	// BONUS: print the value of i here and try to understand why it's 10
+
+	// DO NOT CHANGE THIS
+	assert (count == 10);
+	return 0;
+}
+

exercises/03_for_statement/for_statement_02.c

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+/*
+ * The provided program generates a table of 
+ * temperatures in Fahrenheit and their corresponding 
+ * Celsius equivalents, increasing in steps of 20 degrees from 
+ * 0°F to 300°F. The Celsius temperature is calculated directly 
+ * within the printf statement using a for loop.
+ *
+ * Modify the provided temperature conversion 
+ * C program to print the Fahrenheit to Celsius c
+ * onversion table in reverse order, 
+ * from 0 degrees Fahrenheit up to 300 degrees.
+*/
+
+// ❌ I AM NOT DONE
+
+#include <stdio.h>
+#include <assert.h>
+
+#define TRACK 320
+
+static int track = 0;
+
+// DO NOT CHANGE THIS
+void verify_count (int i) {
+	assert(i == track);
+	track += 20;
+}
+
+int main() {
+	// YOUR CODE HERE
+	for (int fahr = 300; fahr >= 0; fahr -= 20) {
+	// END YOUR CODE
+		printf("%3d %6.1f\n", fahr, (5.0 / 9.0) * (fahr - 32));
+
+		verify_count(fahr); // DO NOT CHANGE THIS
+	}
+
+	// BONUS: print the value of track here 
+	// and try to understand why it's 320
+
+	// DO NOT CHANGE THIS
+	assert (track == TRACK);
+
+	return 0;
+}
+