The C language implementation of URL encode and URL decode, encodedecode

The C language implementation of URL encode and URL decode, encodedecode

Reprinted from: http://blog.csdn.net/langeldep/article/details/6264058

The code in this article is modified from the PHP code, and only two functions are retained.

 

Int php_url_decode (char * str, int len );
Char * php_url_encode (char const * s, int len, int * new_length );

 

URL encoding is performed as follows:

 

Character "a"-"z", "A"-"Z", "0"-"9 ",". ","-"," * ", and" _ "are not encoded to maintain the original value;

Space "" is converted to the plus sign "+ ".

Each other byte is represented as a 3-character string in "% xy" format, encoded as a UTF-8.

# Include <stdio. h> # include <stdlib. h> # include <string. h> # include <ctype. h> # include <sys/types. h> static unsigned char hexchars [] = "0123456789 ABCDEF ";/**
* Convert a hexadecimal number to a hexadecimal number.
* For example, 0xE4 = 14*16 + 4 = 228
*/Static int php_htoi (char * s) {int value; int c; c = (unsigned char *) s) [0]; if (isupper (c )) c = tolower (c); value = (c> = '0' & c <= '9 '? C-'0': c-'A' + 10) * 16; c = (unsigned char *) s) [1]; if (isupper (c )) c = tolower (c); value + = c> = '0' & c <= '9 '? C-'0': c-'A' + 10; return (value);} char * php_url_encode (char const * s, int len, int * new_length) {register unsigned char c; unsigned char * to, * start; unsigned char const * from, * end; from = (unsigned char *) s; end = (unsigned char *) s + len; start = to = (unsigned char *) calloc (1, 3 * len + 1); while (from <end) {c = * from ++; if (c = '') {* to ++ = '+';} else if (c <'0' & c! = '-' & C! = '.') | (C <'A' & c> '9') | (c> 'Z' & c <'A' & c! = '_') | (C> 'Z') {to [0] = '%'; to [1] = hexchars [c> 4]; // convert binary to hexadecimal to [2] = hexchars [c & 15]; // convert binary to hexadecimal to + = 3;} else {* to ++ = c;} * to = 0; if (new_length) {* new_length = to-start;} return (char *) start;} int php_url_decode (char * str, int len) {char * dest = str; char * data = str; while (len --) {if (* data = '+') {* dest = '';} else if (* data = '%' & len> = 2 & isxdigit (Int) * (data + 1) & isxdigit (int) * (data + 2) {* dest = (char) php_htoi (data + 1 ); data + = 2; len-= 2;} else {* dest = * data;} data ++; dest ++;} * dest = '\ 0 '; return dest-str;} int main (int argc, char ** argv) {char * str = "Hello, world! ", * New_str; int len = 0, new_len = 0, old_len = 0; len = strlen (str); new_str = php_url_encode (str, len, & new_len ); printf ("new string: % s, new length: % d \ n", new_str, new_len); old_len = php_url_decode (new_str, new_len); printf ("old string: % s, old length: % d \ n ", new_str, old_len); return 0 ;}

Ps: I checked a lot of information to understand the urldecode principle. It turned out to be so simple.