1 files changed, 36 insertions, 0 deletions
diff --git a/CSAPP/chap2/casting.c b/CSAPP/chap2/casting.c
new file mode 100644
index 0000000..5089802
--- /dev/null
+++ b/CSAPP/chap2/casting.c
@@ -0,0 +1,36 @@
+/*
+ * Shows how the conversion between signed and unsigned are made.
+ * Most machines follow the rule that the underlying bit pattern doesn't change.
+ * Let's see
+ */
+
+#include <stdio.h>
+
+/* 10101010
+ * integers are usually considered signed by default unless we append
+ * the suffix U to the number*/
+#define NUM 0xAA
+int x = -1;
+unsigned u = 2147483648;
+
+int main(void) {
+
+	unsigned char a = NUM;
+	printf("Original unsigned number - HEX: 0x%.2X %d\n", a, a);
+	/* there is no formatter to print a single byte integer, printing it
+	 * with %d would result in a cast to integer, printing 4 bytes, so let's
+	 * print it only in HEX
+	 */
+
+	printf("Signed conversion number - HEX: 0x%.2X DEC: %d\n", (char)a, (signed char)a);
+
+	printf("x = %d - x = %u - 0x%X\n", x, x, x);
+	printf("u = %d - u = %u - 0x%X\n", u, u, u);
+
+	/*
+	 * When one of the operands in an equation is unsigned, C will cast the
+	 * another operand to unsigned too before making the operation
+	 */
+	printf("%X\n", -2147483647);
+	return 0;
+}