类型转换错误问题

[fjl1210]

提示错误信息：
cannot convert parameter 1 from 'class CString *' to 'const char *'
大虾们给我指点看我该怎么改？
调用函数语句如下：
user[i].pass=MDPaint(strpass);//strpass表示用户密码，MDPaint()函数是对其加密后返回值
--------------------------------------
函数定义如下：
int MDPaint(CString *string)
{
MD5_CTX context;
unsigned char digest[16];
memset(digest,0,16);
unsigned int len = strlen(string);
MD5Init(&context);
MD5Update(&context, (unsigned char*)string, len);
MD5Final(digest, &context);
int hex[64];
for(int i = 0;i < 16; i++)
sprintf(hex + i * 2, "%02X", digest[i]);
return hex;
}
//其中这函数定义也是我自个拼凑的，肯定有错误在里面。麻烦大虾们给我指点迷津。谢谢！

[dfyang]

int MDPaint(CString *string)------------->int MDPaint(CString string)
{
MD5_CTX context;
unsigned char digest[16];
memset(digest,0,16);
unsigned int len = strlen(string);-----------------> unsigned int len = string.GetLength();
unsigned char* ch = new char[len];
for(int j=0;j<len;j++) ch[i]=string[i];
string[i]='\0';
MD5Init(&context);
MD5Update(&context, ch, len);
for(int k=0 ;k<len;k++)string[i]=ch[i];
MD5Final(digest, &context);
int hex[64];
for(int i = 0;i < 16; i++)
sprintf(hex + i * 2, "%02X", digest[i]);
return hex;
}

[fjl1210]

谢谢这位大虾，我按你的程序改了，然后出现如下提示问题
int MDPaint(CString string)
{
MD5_CTX context;
unsigned char digest[16];
memset(digest,0,16);
unsigned int len = string.GetLength();
unsigned char* ch = new char[len];
-----------------------------------------------------
//cannot convert from 'char *' to 'unsigned char *'
-----------------------------------------------------
for(int j=0;j<len;j++)
ch[i]=string[i];//i：undeclared identifier
string[i]='\0';//left operand must be l-value
MD5Init(&context);//
MD5Update(&context, ch, len);
for(int k=0 ;k<len;k++)
string[i]=ch[i];//left operand must be l-value
MD5Final(digest, &context);
int hex[64];
for(int i = 0;i < 16; i++)
sprintf(hex + i * 2, "%02X", digest[i]);
//cannot convert parameter 1 from 'int *' to 'char *'
return hex;//返回是一个字符串，而函数定义是整型，这可以么？
}

[fanqing]

(unsigned char*)string改为string.GetBuffer(string.GetLength());
unsigned int len = strlen(string);改为unsigned int len = string.GetLength();