From 1644367743a7e7df4efa3ac9127776e7eac177bd Mon Sep 17 00:00:00 2001
From: leitner <leitner>
Date: Mon, 12 Feb 2024 17:18:44 +0000
Subject: [PATCH] add unit tests, make code more obvious

---
 str/str_chr.c   | 18 ++++++++++--------
 str/str_diffn.c | 13 +++++++++++++
 str/str_len.c   | 10 ++++++++++
 str/str_rchr.c  | 16 ++++++++++++++++
 str/str_start.c | 20 ++++++++++++++++++++
 5 files changed, 69 insertions(+), 8 deletions(-)

diff --git a/str/str_chr.c b/str/str_chr.c
index 418dd57..048deba 100644
--- a/str/str_chr.c
+++ b/str/str_chr.c
@@ -1,19 +1,21 @@
 #include "str.h"
 
 size_t str_chr(const char *in, char needle) {
+#if 0
   register const char* t=in;
   register const char c=needle;
   for (;;) {
-    if (!*t || *t==c) break;
-                             ++t;
-    if (!*t || *t==c) break;
-                             ++t;
-    if (!*t || *t==c) break;
-                             ++t;
-    if (!*t || *t==c) break;
-                             ++t;
+    if (!*t || *t==c) break; else ++t;
+    if (!*t || *t==c) break; else ++t;
+    if (!*t || *t==c) break; else ++t;
+    if (!*t || *t==c) break; else ++t;
   }
   return (size_t)(t-in);
+#else
+  size_t i;
+  for (i=0; in[i] && in[i]!=needle; ++i) ;
+  return i;
+#endif
 }
 
 #ifdef UNITTEST
diff --git a/str/str_diffn.c b/str/str_diffn.c
index 055d432..7dced17 100644
--- a/str/str_diffn.c
+++ b/str/str_diffn.c
@@ -23,3 +23,16 @@ int str_diffn(const char* a, const char* b, size_t limit) {
   }
   return j;
 }
+
+#ifdef UNITTEST
+#include <assert.h>
+#include <string.h>
+
+int main() {
+  assert(str_diffn("foo","foo",3)==0);
+  assert(str_diffn("foo","fob",3)==('o'-'b'));
+  assert(str_diffn("foo","foox",4)==(-'x'));
+  assert(str_diffn("foox","foo",4)=='x');
+  assert(str_diffn("foo","fob",2)==0);
+}
+#endif
diff --git a/str/str_len.c b/str/str_len.c
index 2fe759e..9621518 100644
--- a/str/str_len.c
+++ b/str/str_len.c
@@ -15,3 +15,13 @@ size_t str_len(const char* in) {
   }
   return (size_t)(t-in);
 }
+
+#ifdef UNITTEST
+#include <assert.h>
+int main() {
+  assert(str_len("foo")==3);
+  assert(str_len("")==0);
+  assert(str_len("fnord")==5);
+  return 0;
+}
+#endif
diff --git a/str/str_rchr.c b/str/str_rchr.c
index 595001a..b774e67 100644
--- a/str/str_rchr.c
+++ b/str/str_rchr.c
@@ -1,6 +1,11 @@
 #include "str.h"
 
 size_t str_rchr(const char *in, char needle) {
+#if 1
+  size_t i,j=-1;
+  for (i=0; in[i]; ++i) if (in[i]==needle) j=i;
+  return i<j ? i : j;
+#else
   register const char* t=in;
   register const char c=needle;
   register const char* found=0;
@@ -22,4 +27,15 @@ size_t str_rchr(const char *in, char needle) {
                                         ++t;
   }
   return (size_t)((found?found:t)-in);
+#endif
 }
+
+#ifdef UNITTEST
+#include <assert.h>
+int main() {
+  assert(str_rchr("fnord",'r')==3);
+  assert(str_rchr("frord",'r')==3);
+  assert(str_rchr("fnord",'x')==5);
+  return 0;
+}
+#endif
diff --git a/str/str_start.c b/str/str_start.c
index 5cff770..43639dc 100644
--- a/str/str_start.c
+++ b/str/str_start.c
@@ -2,6 +2,14 @@
 
 /* str_start returns 1 if the b is a prefix of a, 0 otherwise */
 int str_start(const char* a, const char* b) {
+#if 1
+  size_t i;
+  for (i=0; ; ++i) {
+    if (!b[i]) return 1;
+    if (a[i]!=b[i]) break;
+  }
+  return 0;
+#else
   register const char* s=a;
   register const char* t=b;
   for (;;) {
@@ -19,4 +27,16 @@ int str_start(const char* a, const char* b) {
                                           ++s; ++t;
   }
   return 0;
+#endif
+}
+
+#ifdef UNITTEST
+#include <assert.h>
+int main() {
+  assert(str_start("fnord","no")==0);
+  assert(str_start("fnord","fno")==1);
+  assert(str_start("fnord","fnord")==1);
+  assert(str_start("fnord","fnord1")==0);
+  return 0;
 }
+#endif