diff --git a/src/guf_str.h b/src/guf_str.h
index 3f67e63..f678ae0 100644
--- a/src/guf_str.h
+++ b/src/guf_str.h
@@ -90,15 +90,13 @@ GUF_STR_KWRDS void guf_str_free(guf_str *str, void *ctx);
 GUF_STR_KWRDS guf_str *guf_str_copy(guf_str *dst, const guf_str *src, void *ctx);
 GUF_STR_KWRDS guf_str *guf_str_move(guf_str *dst, guf_str *src, void *ctx);
 
+GUF_STR_KWRDS bool guf_str_equal(const guf_str *a, const guf_str *b);
+GUF_STR_KWRDS int guf_str_cmp(const guf_str *a, const guf_str *b);
+
 // TODO:
 GUF_STR_KWRDS guf_str guf_str_try_new_substr(guf_str_view str_view, ptrdiff_t pos, ptrdiff_t len, guf_allocator *alloc, guf_err *err);
 GUF_STR_KWRDS guf_str guf_str_new_substr(guf_str_view str_view, ptrdiff_t pos, ptrdiff_t len, guf_allocator *alloc);
 
-// TODO:
-GUF_STR_KWRDS bool guf_str_equal(const guf_str *a, const guf_str *b);
-GUF_STR_KWRDS bool guf_str_equals_cstr(const guf_str *a, const char *c_str);
-GUF_STR_KWRDS bool guf_str_equals_strview(const guf_str *a,  guf_str_view b);
-
 // DONE: 
 GUF_STR_KWRDS guf_str *guf_str_try_append_char(guf_str *str, char c, ptrdiff_t times, guf_err *err);
 GUF_STR_KWRDS guf_str *guf_str_append_char(guf_str *str, char c, ptrdiff_t times);
@@ -363,7 +361,7 @@ GUF_STR_KWRDS guf_str *guf_str_try_reserve(guf_str *str, ptrdiff_t new_cap_min,
     if (guf_str_is_short_internal_(str)) { // a.) Was short string -> need initial allocation.
         char *c_str_new = str->allocator->alloc(new_cap_min_with_null, str->allocator->ctx);
         if (!c_str_new) {
-            guf_err_set_or_panic(err, GUF_ERR_ALLOC_FAIL, "in guf_str_try_grow_if_necessary: Initial allocation failed.");
+            guf_err_set_or_panic(err, GUF_ERR_ALLOC_FAIL, "in guf_str_try_reserve: Initial allocation failed.");
             return NULL;
         }
         memcpy(c_str_new, str->data.shrt.c_str, len_with_null);
@@ -372,7 +370,7 @@ GUF_STR_KWRDS guf_str *guf_str_try_reserve(guf_str *str, ptrdiff_t new_cap_min,
     } else { // b) Was long string -> need re-allocation
         char *c_str_new = str->allocator->realloc(str->data.lng.c_str, old_cap_with_null, new_cap_min_with_null, str->allocator->ctx);
         if (!c_str_new) {
-            guf_err_set_or_panic(err, GUF_ERR_ALLOC_FAIL, "in guf_str_try_grow_if_necessary: re-allocation failed.");
+            guf_err_set_or_panic(err, GUF_ERR_ALLOC_FAIL, "in guf_str_try_reserve: re-allocation failed.");
             return NULL;
         }
         str->data.lng.c_str = c_str_new;
@@ -557,7 +555,8 @@ GUF_STR_KWRDS guf_str *guf_str_copy(guf_str *dst, const guf_str *src, void *ctx)
     (void)ctx;
     GUF_ASSERT_RELEASE(dst);
     GUF_ASSERT_RELEASE(guf_str_is_valid(src));
-
+    GUF_ASSERT_RELEASE(!guf_str_is_readonly(src)); // // Doesn't make sense to deep-cpy in readonly mode (I think).
+    
     guf_str_init_empty(dst, src->allocator);
     GUF_ASSERT(guf_str_is_short_internal_(dst));
 
@@ -593,13 +592,40 @@ GUF_STR_KWRDS guf_str *guf_str_move(guf_str *dst, guf_str *src, void *ctx)
     (void)ctx;
     GUF_ASSERT_RELEASE(dst);
     GUF_ASSERT_RELEASE(guf_str_is_valid(src));
+    GUF_ASSERT_RELEASE(!guf_str_is_readonly(src)); // Doesn't make sense to move in readonly mode (I think).
+  
     *dst = *src;
     *src = guf_str_new_uninitialised();
     return dst;
 }
 
+GUF_STR_KWRDS bool guf_str_equal(const guf_str *a, const guf_str *b)
+{
+    GUF_ASSERT_RELEASE(guf_str_is_valid(a) && guf_str_is_valid(b));
 
+    if (guf_str_len(a) != guf_str_len(b)) {
+        return false;
+    }
+    const char *a_cstr = guf_str_const_cstr(a);
+    const char *b_cstr = guf_str_const_cstr(b);
+    GUF_ASSERT(a_cstr && b_cstr);
 
+    return 0 == memcmp(a_cstr, b_cstr, guf_str_len(a));
+}
+
+GUF_STR_KWRDS int guf_str_cmp(const guf_str *a, const guf_str *b)
+{
+    GUF_ASSERT_RELEASE(guf_str_is_valid(a) && guf_str_is_valid(b));
+    GUF_ASSERT_RELEASE(guf_str_is_valid(a) && guf_str_is_valid(b));
+
+    
+    const ptrdiff_t shorter_len = guf_min_ptrdiff_t(guf_str_len(a), guf_str_len(b));
+    const char *a_cstr = guf_str_const_cstr(a);
+    const char *b_cstr = guf_str_const_cstr(b);
+    GUF_ASSERT(a_cstr && b_cstr);
+
+    return memcmp(a_cstr, b_cstr, shorter_len);
+}
 
 GUF_STR_KWRDS guf_str *guf_str_try_append_char(guf_str *str, char c, ptrdiff_t times, guf_err *err)
 {
@@ -622,8 +648,9 @@ GUF_STR_KWRDS guf_str *guf_str_try_append_char(guf_str *str, char c, ptrdiff_t t
 
     const size_t old_cap = guf_str_cap_internal_(str);
     const size_t old_len = guf_str_len_internal_(str);
+
     const size_t new_len = old_len + (size_t)times;
-    if (new_len <= old_len || new_len > (size_t)PTRDIFF_MAX) { // Handle overflow.
+    if (new_len <= old_len || new_len >= (size_t)PTRDIFF_MAX) { // Handle overflow.
         guf_err_set_or_panic(err, GUF_ERR_INT_OVERFLOW, "in guf_str_try_append_char: new length would overflow ptrdiff_t");
         return NULL;
     } else if (new_len > old_cap) { // Need to grow capacity.
@@ -686,7 +713,7 @@ GUF_STR_KWRDS guf_str *guf_str_try_append(guf_str *str, guf_str_view sv, guf_err
     const size_t old_cap = guf_str_cap_internal_(str);
     const size_t old_len = guf_str_len_internal_(str);
     const size_t new_len = old_len + (size_t)sv.len;
-    if (new_len <= old_len || new_len > (size_t)PTRDIFF_MAX) { // Handle overflow.
+    if (new_len <= old_len || new_len >= (size_t)PTRDIFF_MAX) { // Handle overflow.
         guf_err_set_or_panic(err, GUF_ERR_INT_OVERFLOW, "in guf_str_try_append_view: new length would overflow ptrdiff_t");
         return NULL;
     }  else if (new_len > old_cap) { // Growth necessary.
@@ -739,7 +766,11 @@ GUF_STR_KWRDS guf_str *guf_str_try_append_cstr(guf_str *str, const char *c_str,
         GUF_ASSERT(len <= cap);
 
         if (len == cap) { // Grow if necessary. 
-            guf_str_try_reserve(str, cap < PTRDIFF_MAX ? cap + 1 : PTRDIFF_MAX, err);
+            if (cap == PTRDIFF_MAX) {
+                guf_err_set_or_panic(err, GUF_ERR_INT_OVERFLOW, "in guf_str_try_append_cstr: cannot grow (capacity is PTRDIFF_MAX)");
+                return NULL;
+            }
+            guf_str_try_reserve(str, cap + 1, err);
             if (err && *err != GUF_ERR_NONE) {
                 guf_err_set_or_panic(err, GUF_ERR_INT_OVERFLOW, "in guf_str_try_append_cstr: failed to reserve");
                 return NULL;