curl_easy_unescape(3) Library Functions Manual curl_easy_unescape(3)

curl_easy_unescape - URL decodes the given string

#include <curl/curl.h>
char *curl_easy_unescape(CURL *curl, const char *input,
                         int inlength, int *outlength);

This function converts the URL encoded string input to a "plain string" and returns that in an allocated memory area. All input characters that are URL encoded (%XX where XX is a two-digit hexadecimal number) are converted to their binary versions.

If the length argument is set to 0 (zero), curl_easy_unescape(3) uses strlen() on input to find out the size.

If outlength is non-NULL, the function writes the length of the returned string in the integer it points to. This allows proper handling even for strings containing %00. Since this is a pointer to an int type, it can only return a value up to INT_MAX so no longer string can be returned in this parameter.

Since 7.82.0, the curl parameter is ignored. Prior to that there was per-handle character conversion support for some old operating systems such as TPF, but it was otherwise ignored.

You must curl_free(3) the returned string when you are done with it.


int main(void)
  CURL *curl = curl_easy_init();
  if(curl) {
    int decodelen;
    char *decoded = curl_easy_unescape(curl, "%63%75%72%6c", 12, &decodelen);
    if(decoded) {
      /* do not assume printf() works on the decoded data! */
      printf("Decoded: ");
      /* ... */

Added in 7.15.4 and replaces the old curl_unescape(3) function.

A pointer to a null-terminated string or NULL if it failed.

curl_easy_escape(3), curl_free(3)

2024-05-22 libcurl