C语言下对字符串进行MD5加密

如题，我在网上找了好多这样的函数，但编译时多多少少都有问题，不能通过，那位大侠能给一个能在VC6下通过的对字符串（字符数组）进行MD5加密的代码，谢谢了！
再次声明，要纯C的不要把什么.CPP的拿上来了，谢谢。

怎么发给你？
md5.h
//===================================================
#ifndef MD5_H
#define MD5_H

#include <string>
#include <fstream>


typedef unsigned char byte;
typedef unsigned int uint32;

using std::string;
using std::ifstream;


class MD5 {
public:
MD5();
MD5(const void* input, size_t length);
MD5(const string& str);
MD5(ifstream& in);
void update(const void* input, size_t length);
void update(const string& str);
void update(ifstream& in);
const byte* digest();
string toString();
void reset();

private:
void update(const byte* input, size_t length);
void final();
void transform(const byte block[64]);
void encode(const uint32* input, byte* output, size_t length);
void decode(const byte* input, uint32* output, size_t length);
string bytesToHexString(const byte* input, size_t length);


MD5(const MD5&);
MD5& operator=(const MD5&);

private:
uint32 _state[4];
uint32 _count[2];
byte _buffer[64];
byte _digest[16];
bool _finished;

static const byte PADDING[64];
static const char HEX[16];
enum { BUFFER_SIZE = 1024 };
};

#endif

md5.cpp
//==============================================
#include "md5.h"

using namespace std;


#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21


#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))


#define ROTATE_LEFt(x, n) (((x) << (n)) | ((x) >> (32-(n))))


#define FF(a, b, c, d, x, s, ac) { \
(a) += F ((b), (c), (d)) + (x) + ac; \
(a) = ROTATE_LEFt ((a), (s)); \
(a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) { \
(a) += G ((b), (c), (d)) + (x) + ac; \
(a) = ROTATE_LEFt ((a), (s)); \
(a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) { \
(a) += H ((b), (c), (d)) + (x) + ac; \
(a) = ROTATE_LEFt ((a), (s)); \
(a) += (b); \
}
#define II(a, b, c, d, x, s, ac) { \
(a) += I ((b), (c), (d)) + (x) + ac; \
(a) = ROTATE_LEFt ((a), (s)); \
(a) += (b); \
}

const byte MD5::PADDING[64] = { 0x80 };
const char MD5::HEX[16] = {
'0', '1', '2', '3',
'4', '5', '6', '7',
'8', '9', 'a', 'b',
'c', 'd', 'e', 'f'
};


MD5::MD5() {
reset();
}


MD5::MD5(const void* input, size_t length) {
reset();
update(input, length);
}


MD5::MD5(const string& str) {
reset();
update(str);
}


MD5::MD5(ifstream& in) {
reset();
update(in);
}


const byte* MD5::digest() {

if (!_finished) {
_finished = true;
final();
}
return _digest;
}


void MD5::reset() {

_finished = false;

_count[0] = _count[1] = 0;

_state[0] = 0x67452301;
_state[1] = 0xefcdab89;
_state[2] = 0x98badcfe;
_state[3] = 0x10325476;
}


void MD5::update(const void* input, size_t length) {
update((const byte*)input, length);
}


void MD5::update(const string& str) {
update((const byte*)str.c_str(), str.length());
}


void MD5::update(ifstream& in) {

if (!in) {
return;
}

std::streamsize length;
char buffer[BUFFER_SIZE];
while (!in.eof()) {
in.read(buffer, BUFFER_SIZE);
length = in.gcount();
if (length > 0) {
update(buffer, length);
}
}
in.close();
}


void MD5::update(const byte* input, size_t length) {

uint32 i, index, partLen;

_finished = false;


index = (uint32)((_count[0] >> 3) & 0x3f);


if ((_count[0] += ((uint32)length << 3)) < ((uint32)length << 3)) {
++_count[1];
}
_count[1] += ((uint32)length >> 29);

partLen = 64 - index;


if (length >= partLen) {

memcpy(&_buffer[index], input, partLen);
transform(_buffer);

for (i = partLen; i + 63 < length; i += 64) {
transform(&input[i]);
}
index = 0;

} else {
i = 0;
}


memcpy(&_buffer[index], &input[i], length - i);
}


void MD5::final() {

byte bits[8];
uint32 oldState[4];
uint32 oldCount[2];
uint32 index, padLen;


memcpy(oldState, _state, 16);
memcpy(oldCount, _count, 8);


encode(_count, bits, 8);


index = (uint32)((_count[0] >> 3) & 0x3f);
padLen = (index < 56) ? (56 - index) : (120 - index);
update(PADDING, padLen);


update(bits, 8);


encode(_state, _digest, 16);


memcpy(_state, oldState, 16);
memcpy(_count, oldCount, 8);
}


void MD5::transform(const byte block[64]) {

uint32 a = _state[0], b = _state[1], c = _state[2], d = _state[3], x[16];

decode(block, x, 64);


FF (a, b, c, d, x[ 0], S11, 0xd76aa478);
FF (d, a, b, c, x[ 1], S12, 0xe8c7b756);
FF (c, d, a, b, x[ 2], S13, 0x242070db);
FF (b, c, d, a, x[ 3], S14, 0xc1bdceee);
FF (a, b, c, d, x[ 4], S11, 0xf57c0faf);
FF (d, a, b, c, x[ 5], S12, 0x4787c62a);
FF (c, d, a, b, x[ 6], S13, 0xa8304613);
FF (b, c, d, a, x[ 7], S14, 0xfd469501);
FF (a, b, c, d, x[ 8], S11, 0x698098d8);
FF (d, a, b, c, x[ 9], S12, 0x8b44f7af);
FF (c, d, a, b, x[10], S13, 0xffff5bb1);
FF (b, c, d, a, x[11], S14, 0x895cd7be);
FF (a, b, c, d, x[12], S11, 0x6b901122);
FF (d, a, b, c, x[13], S12, 0xfd987193);
FF (c, d, a, b, x[14], S13, 0xa679438e);
FF (b, c, d, a, x[15], S14, 0x49b40821);


GG (a, b, c, d, x[ 1], S21, 0xf61e2562);
GG (d, a, b, c, x[ 6], S22, 0xc040b340);
GG (c, d, a, b, x[11], S23, 0x265e5a51);
GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa);
GG (a, b, c, d, x[ 5], S21, 0xd62f105d);
GG (d, a, b, c, x[10], S22, 0x2441453);
GG (c, d, a, b, x[15], S23, 0xd8a1e681);
GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8);
GG (a, b, c, d, x[ 9], S21, 0x21e1cde6);
GG (d, a, b, c, x[14], S22, 0xc33707d6);
GG (c, d, a, b, x[ 3], S23, 0xf4d50d87);
GG (b, c, d, a, x[ 8], S24, 0x455a14ed);
GG (a, b, c, d, x[13], S21, 0xa9e3e905);
GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8);
GG (c, d, a, b, x[ 7], S23, 0x676f02d9);
GG (b, c, d, a, x[12], S24, 0x8d2a4c8a);


HH (a, b, c, d, x[ 5], S31, 0xfffa3942);
HH (d, a, b, c, x[ 8], S32, 0x8771f681);
HH (c, d, a, b, x[11], S33, 0x6d9d6122);
HH (b, c, d, a, x[14], S34, 0xfde5380c);
HH (a, b, c, d, x[ 1], S31, 0xa4beea44);
HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9);
HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60);
HH (b, c, d, a, x[10], S34, 0xbebfbc70);
HH (a, b, c, d, x[13], S31, 0x289b7ec6);
HH (d, a, b, c, x[ 0], S32, 0xeaa127fa);
HH (c, d, a, b, x[ 3], S33, 0xd4ef3085);
HH (b, c, d, a, x[ 6], S34, 0x4881d05);
HH (a, b, c, d, x[ 9], S31, 0xd9d4d039);
HH (d, a, b, c, x[12], S32, 0xe6db99e5);
HH (c, d, a, b, x[15], S33, 0x1fa27cf8);
HH (b, c, d, a, x[ 2], S34, 0xc4ac5665);


II (a, b, c, d, x[ 0], S41, 0xf4292244);
II (d, a, b, c, x[ 7], S42, 0x432aff97);
II (c, d, a, b, x[14], S43, 0xab9423a7);
II (b, c, d, a, x[ 5], S44, 0xfc93a039);
II (a, b, c, d, x[12], S41, 0x655b59c3);
II (d, a, b, c, x[ 3], S42, 0x8f0ccc92);
II (c, d, a, b, x[10], S43, 0xffeff47d);
II (b, c, d, a, x[ 1], S44, 0x85845dd1);
II (a, b, c, d, x[ 8], S41, 0x6fa87e4f);
II (d, a, b, c, x[15], S42, 0xfe2ce6e0);
II (c, d, a, b, x[ 6], S43, 0xa3014314);
II (b, c, d, a, x[13], S44, 0x4e0811a1);
II (a, b, c, d, x[ 4], S41, 0xf7537e82);
II (d, a, b, c, x[11], S42, 0xbd3af235);
II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb);
II (b, c, d, a, x[ 9], S44, 0xeb86d391);

_state[0] += a;
_state[1] += b;
_state[2] += c;
_state[3] += d;
}


void MD5::encode(const uint32* input, byte* output, size_t length) {

for (size_t i = 0, j = 0; j < length; ++i, j += 4) {
output[j]= (byte)(input[i] & 0xff);
output[j + 1] = (byte)((input[i] >> 8) & 0xff);
output[j + 2] = (byte)((input[i] >> 16) & 0xff);
output[j + 3] = (byte)((input[i] >> 24) & 0xff);
}
}


void MD5::decode(const byte* input, uint32* output, size_t length) {

for (size_t i = 0, j = 0; j < length; ++i, j += 4) {
output[i] = ((uint32)input[j]) | (((uint32)input[j + 1]) << 8) |
(((uint32)input[j + 2]) << 16) | (((uint32)input[j + 3]) << 24);
}
}


string MD5::bytesToHexString(const byte* input, size_t length) {

string str;
str.reserve(length << 1);
for (size_t i = 0; i < length; ++i) {
int t = input[i];
int a = t / 16;
int b = t % 16;
str.append(1, HEX[a]);
str.append(1, HEX[b]);
}
return str;
}


string MD5::toString() {
return bytesToHexString(digest(), 16);
}