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Now str_shuffle() has the randomization characteristics of shuffle().

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str_shuffle() won't return anymore the randomized string and thus will be
consistent with shuffle(). Since this function is new to 4.3.0 no BC
problems.
#Thanks to Adam Trachtenberg for providing good example to check the
#permuations distribution.
This commit is contained in:
Andrey Hristov 2002-10-08 09:52:59 +00:00
parent 2005705272
commit 0ad8b4aa10
1 changed files with 28 additions and 18 deletions
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46
ext/standard/string.c
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@ -3995,35 +3995,45 @@ PHP_FUNCTION(str_rot13)
/* }}} */
static int php_string_shuffle(const void *a, const void *b TSRMLS_DC)
static void php_string_shuffle(char *str, long len TSRMLS_DC)
{
long rnd;
rnd = php_rand(TSRMLS_C);
if (rnd % 3)
return 1;
else if (rnd % 5)
return 0;
else
return -1;
long n_elems, rnd_idx, n_left;
char temp;
/* The implementation is stolen from array_data_shuffle */
/* Thus the characteristics of the randomization are the same */
n_elems = len;
if (n_elems <= 1) {
return;
}
n_left = n_elems;
while (--n_left) {
rnd_idx = php_rand(TSRMLS_C);
RAND_RANGE(rnd_idx, 0, n_left, PHP_RAND_MAX);
if (rnd_idx != n_left) {
temp = str[n_left];
str[n_left] = str[rnd_idx];
str[rnd_idx] = temp;
}
}
}
/* {{{ proto string str_shuffle(string str)
/* {{{ proto void str_shuffle(string str)
Shuffles string. One permutation of all possible is created */
PHP_FUNCTION(str_shuffle)
{
/* Note : by using current php_string_shuffle for string */
/* with 6 chars (6! permutations) about 2/3 of them are */
/* computed for 6! calls for the function. So it isn't so */
/* unique. The ratio is the same for other lengths. */
char *str;
int i, str_len;
int str_len;
i = 0;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &str, &str_len) == FAILURE) {
RETURN_FALSE;
}
zend_qsort((void *)str, str_len, sizeof(char), php_string_shuffle TSRMLS_CC);
RETURN_STRINGL(str, str_len, 1);
php_string_shuffle(str, str_len TSRMLS_CC);
return;
}
/* }}} */