curl_easy_unescape(3) Library Functions Manual curl_easy_unescape(3)
NAME
curl_easy_unescape - URL decode a string
SYNOPSIS
#include <curl/curl.h>
char *curl_easy_unescape(CURL *curl, const char *input,
int inlength, int *outlength);
DESCRIPTION
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.
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
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: ");
/* ... */
curl_free(decoded);
}
curl_easy_cleanup(curl);
}
}
AVAILABILITY
Added in curl 7.15.4
RETURN VALUE
A pointer to a null-terminated string or NULL if it failed.
SEE ALSO
curl_easy_escape(3), curl_url_get(3)
libcurl 2026-07-12 curl_easy_unescape(3)
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