Question

I have this code that show me correctly, the md5 of a string.
I prefer to return a string to the function, but I have some problem converting the values of md5 into my string.
This is the code:

string calculatemd5(string msg)
{
string result;
const char* test = msg.c_str();
int i;

MD5_CTX md5;

MD5_Init (&md5);
MD5_Update (&md5, (const unsigned char *) test, msg.length());
unsigned char buffer_md5[16];
MD5_Final ( buffer_md5, &md5);
printf("Input: %s", test);
printf("\nMD5: ");
for (i=0;i<16;i++){
    printf ("%02x", buffer_md5[i]);
    result[i]=buffer_md5[i];
}
std::cout <<"\nResult:"<< result[i]<<endl;
return result;
}

For example result[i] is a strange ascii char like this: .
How can is possible solve this problem?

Answer 1

replace

for (i=0;i<16;i++){
    printf ("%02x", buffer_md5[i]);
    result[i]=buffer_md5[i];
}

with

char buf[32];
for (i=0;i<16;i++){
    sprintf(buf, "%02x", buffer_md5[i]);
    result.append( buf );
}

notice that when you print out result, print result, not result[i] to get whole string.

if you put the buffer_md5[i] value directly in result then you may get problems since a string may not have an embedded 0 (if there is one).