From 224300e1cf146572e16a776745bc3dd79e716ec1 Mon Sep 17 00:00:00 2001
From: Dan Buch <dan@meatballhat.com>
Date: Fri, 19 Apr 2024 21:51:42 -0400
Subject: [PATCH] Up through lcthw ex 15

---
 lcthw/.gitignore | 12 ++----------
 lcthw/Makefile   |  8 ++++----
 lcthw/ex15.c     | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 14 deletions(-)
 create mode 100644 lcthw/ex15.c

diff --git a/lcthw/.gitignore b/lcthw/.gitignore
index 8942676..9b8cce7 100644
--- a/lcthw/.gitignore
+++ b/lcthw/.gitignore
@@ -1,10 +1,2 @@
-ex1
-ex3
-ex7
-ex8
-ex9
-ex10
-ex11
-ex12
-ex13
-ex14
+ex*
+!ex*.c
diff --git a/lcthw/Makefile b/lcthw/Makefile
index 7e2b449..e7819b5 100644
--- a/lcthw/Makefile
+++ b/lcthw/Makefile
@@ -19,17 +19,17 @@ clean:
 build: $(BUILD_TARGETS)
 
 .PHONY: gtest
-gtest:
+gtest: $(BUILD_TARGETS)
 	@$(foreach bt, $(BUILD_TARGETS), make .gtest.$(bt) &&) printf '\ngYAY\n'
 
-.gtest.%:
+.gtest.%: %
 	@if test -f .$*.argv; then readarray -t test_argv <.$*.argv; fi && \
 	printf '\n==> %s\n' "$*" && $(GDBRUN) ./$* "$${test_argv[@]}"
 
 .PHONY: test
-test:
+test: $(BUILD_TARGETS)
 	@$(foreach bt, $(BUILD_TARGETS), make .test.$(bt) &&) printf '\nYAY\n'
 
-.test.%:
+.test.%: %
 	@if test -f .$*.argv; then readarray -t test_argv <.$*.argv; fi && \
 	printf '\n==> %s\n' "$*" && ./$* "$${test_argv[@]}"
diff --git a/lcthw/ex15.c b/lcthw/ex15.c
new file mode 100644
index 0000000..2a45c30
--- /dev/null
+++ b/lcthw/ex15.c
@@ -0,0 +1,48 @@
+#include <stdio.h>
+
+int main(int argc, char *argv[])
+{
+	// create two arrays we care about
+	int ages[] = { 23, 43, 12, 89, 2 };
+	char *names[] = {
+		"Alan", "Frank",
+		"Mary", "John", "Lisa"
+	};
+
+	// safely get the size of ages
+	int count = sizeof(ages) / sizeof(int);
+	int i = 0;
+
+	// first way using indexing
+	for (i = 0; i < count; i++) {
+		printf("%s has %d years alive.\n", names[i], ages[i]);
+	}
+
+	printf("---\n");
+
+	// setup the pointers to the start of the arrays
+	int *cur_age = ages;
+	char **cur_name = names;
+
+	// second way using pointers
+	for (i = 0; i < count; i++) {
+		printf("%s is %d years old.\n", *(cur_name + i), *(cur_age + i));
+	}
+
+	printf("---\n");
+
+	// third way, pointers are just arrays
+	for (i = 0; i < count; i++) {
+		printf("%s is %d years old again.\n", cur_name[i], cur_age[i]);
+	}
+
+	printf("---\n");
+
+	// fourth way with pointers in a stupid complex way
+	for (cur_name = names, cur_age = ages;
+			(cur_age - ages) < count; cur_name++, cur_age++) {
+		printf("%s lived %d years so far.\n", *cur_name, *cur_age);
+	}
+
+	return 0;
+}