Helper functions for strto...() functions.

[pdclib.old] / functions / _PDCLIB / strtox_prelim.c

diff --git a/functions/_PDCLIB/strtox_prelim.c b/functions/_PDCLIB/strtox_prelim.c
new file mode 100644 (file)
index 0000000..8b0f442
--- /dev/null
+++ b/functions/_PDCLIB/strtox_prelim.c
@@ -0,0 +1,77 @@
+/* $Id$ */
+
+/* Release $Name$ */
+
+/* _PDCLIB_strtox_prelim( const char *, char *, int * )
+
+   This file is part of the Public Domain C Library (PDCLib).
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#include <ctype.h>
+
+const char * _PDCLIB_strtox_prelim( const char * p, char * sign, int * base )
+{
+    /* skipping leading whitespace */
+    while ( isspace( *p ) ) ++p;
+    /* determining / skipping sign */
+    if ( *p != '+' && *p != '-' ) *sign = '+';
+    else *sign = *(p++);
+    /* determining base */
+    if ( *p == '0' )
+    {
+        ++p;
+        if ( ( *base == 0 || *base == 16 ) && ( *p == 'x' || *p == 'X' ) )
+        {
+            *base = 16;
+            ++p;
+        }
+        else if ( *base == 0 )
+        {
+            *base = 8;
+        }
+        else
+        {
+            --p;
+        }
+    }
+    else if ( ! *base )
+    {
+        *base = 10;
+    }
+    return p;
+}
+
+#ifdef TEST
+#include <_PDCLIB_test.h>
+
+int main()
+{
+    int base = 0;
+    char sign = '\0';
+    char test1[] = "  123";
+    char test2[] = "\t+0123";
+    char test3[] = "\v-0x123";
+    BEGIN_TESTS;
+    TESTCASE( _PDCLIB_strtox_prelim( test1, &sign, &base ) == &test1[2] );
+    TESTCASE( sign == '+' );
+    TESTCASE( base == 10 );
+    base = 0;
+    sign = '\0';
+    TESTCASE( _PDCLIB_strtox_prelim( test2, &sign, &base ) == &test2[3] );
+    TESTCASE( sign == '+' );
+    TESTCASE( base == 8 );
+    base = 0;
+    sign = '\0';
+    TESTCASE( _PDCLIB_strtox_prelim( test3, &sign, &base ) == &test3[4] );
+    TESTCASE( sign == '-' );
+    TESTCASE( base == 16 );
+    base = 10;
+    sign = '\0';
+    TESTCASE( _PDCLIB_strtox_prelim( test3, &sign, &base ) == &test3[2] );
+    TESTCASE( sign == '-' );
+    TESTCASE( base == 10 );
+    return TEST_RESULTS;
+}
+
+#endif