add string/array comparision functions

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 122 insertions, 0 deletions

diff --git a/src/string/strcmp.c b/src/string/strcmp.c
new file mode 100644
index 0000000..966bb06
--- /dev/null
+++ b/src/string/strcmp.c
@@ -0,0 +1,122 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <string.h>
+#include <strings.h>
+#include <stddef.h>
+#include <inttypes.h>
+#include <ctype.h>
+
+
+
+/**
+ * Compare two memory segments alphabetically in a case sensitive manner.
+ * 
+ * @param   a     A negetive value is returned if this is the lesser.
+ * @param   b     A positive value is returned if this is the lesser.
+ * @param   size  The size of the segments.
+ * @return        Zero is returned if `a` and `b` are equal, otherwise,
+ *                see the specifications for `a` and `b`.
+ */
+int memcmp(const void* a, const void* b, size_t size)
+{
+  const signed char* s1 = a;
+  const signed char* s2 = b;
+  while (size--)
+    if (*s1 == *s2)
+      s1++, s2++;
+    else
+      return (int)(*s1 - *s2);
+  return 0;
+}
+
+
+/**
+ * Compare two strings alphabetically in a case sensitive manner.
+ * 
+ * @param   a  A negetive value is returned if this is the lesser.
+ * @param   b  A positive value is returned if this is the lesser.
+ * @return     Zero is returned if `a` and `b` are equal, otherwise,
+ *             see the specifications for `a` and `b`.
+ */
+int strcmp(const char* a, const char* b)
+{
+  size_t n = strlen(a);
+  size_t m = strlen(b);
+  return memcmp(a, b, (n < m ? n : m) + 1);
+}
+
+
+/**
+ * Compare two strings alphabetically in a case insensitive manner.
+ * Be aware, only ASCII characters are case insensitive, non-ASCII
+ * characters are case sensitive.
+ * 
+ * @param   a  A negetive value is returned if this is the lesser.
+ * @param   b  A positive value is returned if this is the lesser.
+ * @return     Zero is returned if `a` and `b` are equal, otherwise,
+ *             see the specifications for `a` and `b`.
+ */
+int strcasecmp(const char* a, const char* b)
+{
+  return strncasecmp(a, b, SIZE_MAX);
+}
+
+
+/**
+ * Compare two strings alphabetically in a case sensitive manner.
+ * 
+ * @param   a       A negetive value is returned if this is the lesser.
+ * @param   b       A positive value is returned if this is the lesser.
+ * @param   length  The maximum number of characters to compare.
+ * @return          Zero is returned if `a` and `b` are equal, otherwise,
+ *                  see the specifications for `a` and `b`.
+ */
+int strncmp(const char* a, const char* b, size_t length)
+{
+  size_t n = strnlen(a, length);
+  size_t m = strnlen(b, length);
+  int r = memcmp(a, b, (n < m ? n : m));
+  return r ? r : n == m ? 0 : n < m ? -1 : +1;
+}
+
+
+/**
+ * Compare two strings alphabetically in a case insensitive manner.
+ * Be aware, only ASCII characters are case insensitive, non-ASCII
+ * characters are case sensitive.
+ * 
+ * @param   a       A negetive value is returned if this is the lesser.
+ * @param   b       A positive value is returned if this is the lesser.
+ * @param   length  The maximum number of characters to compare.
+ * @return          Zero is returned if `a` and `b` are equal, otherwise,
+ *                  see the specifications for `a` and `b`.
+ */
+int strncasecmp(const char* a, const char* b, size_t length)
+{
+  int c1, c2;
+  for (; size--; a++, b++)
+    if (*a != *b)
+      {
+	c1 = isalpha(*a) ? tolower(*a) : (int)*a;
+	c2 = isalpha(*b) ? tolower(*b) : (int)*b;
+	if ((c1 -= c2))
+	  return c1;
+      }
+  return 0;
+}
+