CURLOPT_EXPECT_100_TIMEOUT_MS(3)

💅 CURLOPT_EXPECT_100_TIMEOUT_MS(3) — Library Functions Manual 💅

Okay bestie, welcome to the manual page for CURLOPT_EXPECT_100_TIMEOUT_MS(3) from the libcurl Library Functions Manual. We're talking timeout for the Expect: 100-continue response, and it's giving very specific main character energy: how long does libcurl wait before it stops waiting? Let's get into it. 🦋

🌸 NAME 🌸

CURLOPT_EXPECT_100_TIMEOUT_MS — timeout for the Expect: 100-continue response. That's the name, that's the vibe, no notes. 💅

✨ SYNOPSIS ✨

Copy this exactly, bestie — headers and signatures are sacred. 🧚

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_EXPECT_100_TIMEOUT_MS,
                          long milliseconds);

🦋 DESCRIPTION 🦋

So you pass a long, and that's you telling libcurl the number of milliseconds to wait for a server response with HTTP status 100 (Continue), 417 (Expectation Failed), or similar. This is after sending an HTTP request that contains an Expect: 100-continue header. The way that timeout works? It's literally just a countdown for that response. ⏳

Now the important part: if this times out before a response is received, the request body is sent anyway. Not a drill. 😭 So the body is not held hostage forever — it just gets sent without that wait. That's the behavior, periodt.

🎀 DEFAULT 🎀

The default is 1000 milliseconds. One whole second of waiting, periodt. 🎀

🌈 PROTOCOLS 🌈

This functionality affects http only. That's it — only HTTP is invited to this party. 🌈

🍓 EXAMPLE 🍓

Here's the example, and yes, it's exact:

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

    /* wait 3 seconds for 100-continue */
    curl_easy_setopt(curl, CURLOPT_EXPECT_100_TIMEOUT_MS, 3000L);

    curl_easy_perform(curl);
  }
}

See how it sets CURLOPT_EXPECT_100_TIMEOUT_MS to 3000L? That's three seconds of waiting for 100-continue, and the comment says it exactly. Obsessed with clarity. 💖

👑 AVAILABILITY 👑

Added in curl 7.36.0. So if you're on something older, this option is not in the group chat. 👑

💜 RETURN VALUE 💜

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK. Non-zero means an error occurred — see libcurl-errors(3) for the whole lore drop. 💜

🔥 SEE ALSO 🔥

• CURLOPT_HTTPPOST(3) — go check it, bestie.
• CURLOPT_POST(3) — also on the reading list. 🔥

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💖 That's the whole page, bestie — this is the libcurl manual page dated 2026-10-12, and its footer files it under CURLOPT_EX..._TIMEOUT_MS(3). Slay, and happy waiting. 🫶