X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=functions%2Fstring%2Fstrncmp.c;h=1c73e998340e4004a2b7d75718f9d5dd4213877b;hb=e1c526e9bad3f6e69391e94059096145390508d3;hp=d0434a54f3b53f38747b51fbd7c461899883de14;hpb=34893ecc2200dc7017c36a54cb6c5f4c2378b5ec;p=pdclib

diff --git a/functions/string/strncmp.c b/functions/string/strncmp.c
index d0434a5..1c73e99 100644
--- a/functions/string/strncmp.c
+++ b/functions/string/strncmp.c
@@ -1,8 +1,52 @@
-// ----------------------------------------------------------------------------
-// $Id$
-// ----------------------------------------------------------------------------
-// Public Domain C Library - http://pdclib.sourceforge.net
-// This code is Public Domain. Use, modify, and redistribute at will.
-// ----------------------------------------------------------------------------
-
-int strncmp( const char * s1, const char * s2, size_t n ) { /* TODO */ };
+/* strncmp( const char *, const char *, size_t )
+
+   This file is part of the Public Domain C Library (PDCLib).
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#include <string.h>
+
+#ifndef REGTEST
+
+int strncmp( const char * s1, const char * s2, size_t n )
+{
+    while ( *s1 && n && ( *s1 == *s2 ) )
+    {
+        ++s1;
+        ++s2;
+        --n;
+    }
+    if ( n == 0 )
+    {
+        return 0;
+    }
+    else
+    {
+        return ( *(unsigned char *)s1 - *(unsigned char *)s2 );
+    }
+}
+
+#endif
+
+#ifdef TEST
+#include <_PDCLIB_test.h>
+
+int main( void )
+{
+    char cmpabcde[] = "abcde\0f";
+    char cmpabcd_[] = "abcde\xfc";
+    char empty[] = "";
+    char x[] = "x";
+    TESTCASE( strncmp( abcde, cmpabcde, 5 ) == 0 );
+    TESTCASE( strncmp( abcde, cmpabcde, 10 ) == 0 );
+    TESTCASE( strncmp( abcde, abcdx, 5 ) < 0 );
+    TESTCASE( strncmp( abcdx, abcde, 5 ) > 0 );
+    TESTCASE( strncmp( empty, abcde, 5 ) < 0 );
+    TESTCASE( strncmp( abcde, empty, 5 ) > 0 );
+    TESTCASE( strncmp( abcde, abcdx, 4 ) == 0 );
+    TESTCASE( strncmp( abcde, x, 0 ) == 0 );
+    TESTCASE( strncmp( abcde, x, 1 ) < 0 );
+    TESTCASE( strncmp( abcde, cmpabcd_, 10 ) < 0 );
+    return TEST_RESULTS;
+}
+#endif