Greetings!

I was trying to translate an example code snippets from curl which demonstrates how to sending an email via smtp using curl api.The orignal c code works fine,but my D code failed at the beginnig when it is running.

Appreicate for the help to figure me out what's wrong with the code.

dmd v2.106.0 , VS community 2019,Win10 64bit
'''
call dmd -m64 curl.lib sendmail.d && sendmail

• No URL set!
  curl_easy_perform() failed:URL using bad/illegal format or missing URL

'''

D source:

'''
import core.stdc.stdio;
import core.stdc.string;
import core.stdc.stdlib;
import etc.c.curl;
//import std.conv;
//import std.string;

pragma(lib,"curl.lib");

const PASSWORD="real_pass_word";
const FROM_ADDR="sender_email@add.ress";
const TO_ADDR="receiver_email@add.ress";
const CC_ADDR="cc_copy_email@add.ress";

const FROM_MAIL="sender_email@add.ress";
const TO_MAIL="receiver_email@add.ress";
const CC_MAIL="cc_copy_email@add.ress";

const SMTP_VALUE="smtp://smtp-mail.outlook.com:25";//M$ outlook.com mail SMTP...

//static const char* payload_text=cast(const char*)(

enum contents=(
    "To: " ~ TO_MAIL ~ "\r\n" ~
    "From: " ~ FROM_MAIL ~ "\r\n" ~
    "Cc: " ~ CC_MAIL  ~ "\r\n" ~
    "\r\n" ~
    "Subject: SMTP example message" ~ "\r\n" ~
    "\r\n" ~
    "The body of the message starts here." ~ "\r\n" ~
    "\r\n" ~
    "It could be a lot of lines, could be MIME encoded, whatever.\r\n\r\nGood Luck!\r\nGood Luck!" ~ "\r\n");

static const char* payload_text= cast(const char*)contents.ptr;

struct upload_status
{
	size_t bytes_read;
}

static size_t payload_source(char* ptr,size_t size,size_t nmemb,void* userp)
{
	upload_status* upload_ctx=cast(upload_status*)userp;
	//char* data;
	size_t room=size*nmemb;
	
	if((size==0)||(nmemb==0)||((size*nmemb)<1))
	{
		return 0;
	}
	
	const char* data=&payload_text[upload_ctx.bytes_read];
	//const char* data=null;
	//memcpy(cast(void*)data,cast(void*)payload_text,upload_ctx.bytes_read);
	if(data)
	{
		size_t len=strlen(data);
		if(room<len)
		{
			len=room;
		}
		memcpy(ptr,data,len);
		upload_ctx.bytes_read+=len;
		
		return len;
	}
	return 0;
	
}
//extern(C) int main(int argc,char** argv) ---> betterC ? no
void main()
{

	CURL* curl;
	CURLcode res=CurlError.ok;
	curl_slist* recipents=null;
	upload_status upload_ctx={0};
	
	curl=curl_easy_init();
	
	if(curl)
	{
		curl_easy_setopt(curl,CurlProto.smtp,SMTP_VALUE.ptr);
		
		curl_easy_setopt(curl,CurlOption.username,FROM_MAIL.ptr);
		curl_easy_setopt(curl,CurlOption.mail_from,FROM_ADDR.ptr);
		curl_easy_setopt(curl,CurlOption.password,PASSWORD.ptr);
		
		recipents=curl_slist_append(recipents,TO_ADDR.ptr);
		recipents=curl_slist_append(recipents,CC_ADDR.ptr);
		curl_easy_setopt(curl,CurlOption.mail_rcpt,recipents);
		
		curl_easy_setopt(curl,CurlOption.readfunction,&payload_source);
		curl_easy_setopt(curl,CurlOption.readdata,&upload_ctx);
		curl_easy_setopt(curl,CurlOption.verbose,1);
		curl_easy_setopt(curl,CurlOption.upload,1);
		curl_easy_setopt(curl,CurlOption.use_ssl,CurlUseSSL.all);
		
		curl_easy_setopt(curl,CurlOption.ssl_verifypeer,0);
		
		res=curl_easy_perform(curl);
		
		if(res!=CurlError.ok)
		{
			fprintf(stderr,"curl_easy_perform() failed:%s\n",curl_easy_strerror(res));
		}
		
		curl_slist_free_all(recipents);
		
		
		curl_easy_cleanup(curl);
	}
	
	getchar();
	
	//return 0;
	
}

'''