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/* _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>
#include <stddef.h>
#include <string.h>
#ifndef REGTEST
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;
/* catching a border case here: "0x" followed by a non-digit should
be parsed as the unprefixed zero.
We have to "rewind" the parsing; having the base set to 16 if it
was zero previously does not hurt, as the result is zero anyway.
*/
if ( memchr( _PDCLIB_digits, tolower( *p ), *base ) == NULL )
{
p -= 2;
}
}
else if ( *base == 0 )
{
*base = 8;
/* back up one digit, so that a plain zero is decoded correctly
(and endptr is set correctly as well).
(2019-01-15, Giovanni Mascellani)
*/
--p;
}
else
{
--p;
}
}
else if ( ! *base )
{
*base = 10;
}
return ( ( *base >= 2 ) && ( *base <= 36 ) ) ? p : NULL;
}
#endif
#ifdef TEST
#include "_PDCLIB_test.h"
int main( void )
{
#ifndef REGTEST
int base = 0;
char sign = '\0';
char test1[] = " 123";
char test2[] = "\t+0123";
char test3[] = "\v-0x123";
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[2] );
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 );
base = 1;
TESTCASE( _PDCLIB_strtox_prelim( test3, &sign, &base ) == NULL );
base = 37;
TESTCASE( _PDCLIB_strtox_prelim( test3, &sign, &base ) == NULL );
#endif
return TEST_RESULTS;
}
#endif
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