feat: (cstr) strupcase, strdowncase

lib/cstr.c

@@ -73,3 +73,25 @@ strcount (const char *str, char c)
     
     return count;
 }
+
+void
+strdowncase (char *str)
+{
+    while (*str)
+    {
+        if (isupper (*str))
+            *str += 0x20;
+        str++;
+    }
+}
+
+void
+strupcase (char *str)
+{
+    while (*str)
+    {
+        if (islower (*str))
+            *str -= 0x20;
+        str++;
+    }
+}

lib/inc/cstr.h

@@ -7,5 +7,7 @@ char *strtrim (char *str); /* trim whitespace of a cstring (both beginning and e
 char *strtriml (char *str); /* trim whitespace of a cstring on the left (beginning of string). */
 size_t strtrimr (char *str); /* trim whitespace of a cstring on the right (end of string) */
 size_t strcount (const char *str, char c);
+void strdowncase (char *str);
+void strupcase (char *str);
 
 #endif // CUTILS_CSTR_H_

test/main.c

@@ -34,6 +34,13 @@ test_cstr (void)
     test_add (&suite, test_assert_op (strcount (s3, 'l'), ==, 3), "strcount multiple occurances");
     test_add (&suite, test_assert_op (strcount (s3, '\n'), ==, 1), "strcount one occurance");
     test_add (&suite, test_assert_op (strcount (s3, 'X'), ==, 0), "strcount no occurance");
+
+    char s4[] = "Hello, World!\n";
+    char s5[] = "Hello, World!\n";
+    strdowncase (s4);
+    strupcase (s5);
+    test_add (&suite, test_assert (!strcmp (s4, "hello, world!\n")), "strdowncase");
+    test_add (&suite, test_assert (!strcmp (s5, "HELLO, WORLD!\n")), "strupcase");
     
     return test_suite_get_results (&suite);
 }