http://www.eyny.com/viewthread.php?tid=5714235

Ans.txt

real
real
real
real
fake
fake
real
real
real
real
real
real
real
real
fake
fake
real
fake
fake
real
real
fake
fake
fake
fake
fake
fake
fake
real
fake
fake
fake
real
fake
fake

main.c

// Integrated Development Environment
// Visual C++
#include <stdio.h>
#include <stdlib.h>
#include "twidc.h"
//
int main(int argc, char* argv[])
{
	Id id;
	char IptBfr[1024] = "";
	//printf("Input an ID: "), scanf("%s", IptBfr);
	//
	// Cmdline: twidc.exe < TestData.txt
	while ( scanf("%s", IptBfr) != EOF )
	{
		if ( SetTwId(&id, IptBfr) == 1 )
		{
			printf("%s\n", ((IsTwId(&id) == 1)?"real":"fake"));
		}
		else
		{
			printf("failed\n");
		}
	}
	//
	//system("PAUSE");
	return (0);
}

TestData.txt

W211190876
A164416414
P198743888
H189799297
G502860248
D598407636
Z224235385
D185871016
S257694567
G253102416
X257101944
X217849232
X219760083
K106642271
B740948824
F517115276
B423221685
H618927954
H427793198
G509006138
D133604236
J344606618
E963788291
B542097372
G016575412
D123341138
A014607177
H733599818
X278114745
C660380125
A947835120
B640618984
Z283280955
B439880877
I383710734

twidc.c

#include "twidc.h"
//
Local LocalTable[] = 
{
	{'A', 10}, {'B', 11}, {'C', 12}, {'D', 13}, {'E', 14}, 
	{'F', 15}, {'G', 16}, {'H', 17}, {'I', 34}, {'J', 18}, 
	{'K', 19}, {'L', 20}, {'M', 21}, {'N', 22}, {'O', 35}, 
	{'P', 23}, {'Q', 24}, {'R', 25}, {'S', 26}, {'T', 27}, 
	{'U', 28}, {'V', 29}, {'W', 32}, {'X', 30}, {'Y', 31}, 
	{'Z', 33}
};
int LocalLength = (int)(sizeof(LocalTable) / sizeof(LocalTable[0]));
//
int SetTwId(Id* id, const char* idstr)
{
	unsigned int len = 0;
	int i = 0;
	for (; idstr[len] != (char)NULL; len ++);
	if ( len != IDSIZE )
	{
		return (0);
	}
	memset(id, 0, sizeof(Id));
	id->m_uppercase = idstr[0];
	// Return to uppercase
	for (; i < LocalLength; i ++)
	{
		if ( id->m_uppercase == ('a' + i) )
		{
			id->m_uppercase = ('A' + i);
			break;
		}
	}
	memcpy(id->m_number, (idstr + 1), (IDSIZE - 1));
	return (1);
}
int IsTwId(Id* id)
{
	int nRet = 0;
	int i = 0, NumberLength = 9, nValue = 0, nParam = 0;
	for (; i < LocalLength; i ++)
	{
		if ( id->m_uppercase == LocalTable[i].m_code )
		{
			nValue += (LocalTable[i].m_value / 10);
			nValue += ((LocalTable[i].m_value % 10) * 9);
			break;
		}
	}
	for (i = 0; i < NumberLength; i ++)
	{
		nParam = (NumberLength - i - 1);
		if ( nParam == 0 )
		{
			nParam = 1;
		}
		nValue += ((id->m_number[i] - '0') * nParam);
	}
	if ( (nValue % 10) == 0 )
	{
		nRet = 1;
	}
	return nRet;
}

twidc.h

#ifndef _TWIDC_H_
#define _TWIDC_H_
#include <stdio.h>
#include <memory.h>
//
#define IDSIZE 10
//
struct SLocal
{
	char m_code;
	int m_value;
};
typedef struct SLocal Local;
//
struct SIdentification
{
	// Uppercase
	char m_uppercase;
	// Number String
	char m_number[IDSIZE];
};
typedef struct SIdentification Id;
//
// Set ID string to struct Id
// Return 1 is true; Return 0 is false
int SetTwId(Id* id, const char* idstr);
//
// Return 1 is true; Return 0 is false
int IsTwId(Id* id);
//
#endif