curl / libcurl / API / curl_easy_unescape

curl_easy_unescape - URL decode the given string


curl_easy_unescape - URL decodes the given string


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


This function converts the given URL encoded input string 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 will use strlen() on the input url string to find out the size.

If outlength is non-NULL, the function will write 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 very old operating systems such as TPF, but it was otherwise ignored.

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


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 function.

Return value

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

See also

curl_easy_escape(3), curl_free(3),RFC3986

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