CURLOPT_POSTFIELDSIZE - size of POST data pointed to

Added in curl 7.2

-1

If you want to post static data to the server without having libcurl do a strlen() to measure the data size, this option must be used. When this option is used you can post fully binary data, which otherwise is likely to fail. If this size is set to -1, libcurl uses strlen() to get the size or relies on the CURLOPT_READFUNCTION(3) (if used) to signal the end of data. If you post more than 2GB, use CURLOPT_POSTFIELDSIZE_LARGE(3).

#include <string.h> /* for strlen */ int main(void) { CURL *curl = curl_easy_init(); if(curl) { const char *data = "data to send"; curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); /* size of the POST data */ curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, (long) strlen(data)); curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data); curl_easy_perform(curl); } }

CURLOPT_POSTFIELDSIZE - size of POST data pointed to

This functionality affects http only

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).

CURLOPT_POSTFIELDS(3), CURLOPT_POSTFIELDSIZE_LARGE(3) libcurl 2025-06-16 CURLOPT_POSTFIELDSIZE(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_POSTFIELDSIZE, long size);