bool natsort ( array &$array ) 
This function implements a sort algorithm that orders alphanumeric strings in the way a human being would while maintaining key/value associations. This is described as a "natural ordering". An example of the difference between this algorithm and the regular computer string sorting algorithms (used in sort()) can be seen in the example below.

據(jù)官方手冊(cè)還可以得到這樣的結(jié)果：

img1.png img2.png img10.png img12.png

顯然這很適合對(duì)類(lèi)似文件名的排序。從結(jié)果看這種自然算法應(yīng)該是去掉頭和尾的非數(shù)字部分，然后對(duì)留下來(lái)的數(shù)字部分進(jìn)行排序，究竟是不是，還是看一下php源碼吧。

復(fù)制代碼代碼如下:

//從ext/standard/array.c抽取的相關(guān)代碼如下 
static int php_array_natural_general_compare(const void *a, const void *b, int fold_case) /* {{{ */ 
{ 
    Bucket *f, *s; 
    zval *fval, *sval; 
    zval first, second; 
    int result; 
    f = *((Bucket **) a); 
    s = *((Bucket **) b); 
    fval = *((zval **) f->pData); 
    sval = *((zval **) s->pData); 
    first = *fval; 
    second = *sval; 
    if (Z_TYPE_P(fval) != IS_STRING) { 
        zval_copy_ctor(&first); 
        convert_to_string(&first); 
    } 
    if (Z_TYPE_P(sval) != IS_STRING) { 
        zval_copy_ctor(&second); 
        convert_to_string(&second); 
    } 
    result = strnatcmp_ex(Z_STRVAL(first), Z_STRLEN(first), Z_STRVAL(second), Z_STRLEN(second), fold_case); 
    if (Z_TYPE_P(fval) != IS_STRING) { 
        zval_dtor(&first); 
    } 
    if (Z_TYPE_P(sval) != IS_STRING) { 
        zval_dtor(&second); 
    } 
    return result; 
} 
/* }}} */ 
static int php_array_natural_compare(const void *a, const void *b TSRMLS_DC) /* {{{ */ 
{ 
    return php_array_natural_general_compare(a, b, 0); 
} 
/* }}} */ 
static void php_natsort(INTERNAL_FUNCTION_PARAMETERS, int fold_case) /* {{{ */ 
{ 
    zval *array; 
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "a", &array) == FAILURE) { 
        return; 
    } 
    if (fold_case) { 
        if (zend_hash_sort(Z_ARRVAL_P(array), zend_qsort, php_array_natural_case_compare, 0 TSRMLS_CC) == FAILURE) { 
            return; 
        } 
    } else { 
        if (zend_hash_sort(Z_ARRVAL_P(array), zend_qsort, php_array_natural_compare, 0 TSRMLS_CC) == FAILURE) { 
            return; 
        } 
    } 
    RETURN_TRUE; 
} 
/* }}} */ 
/* {{{ proto void natsort(array &array_arg) 
Sort an array using natural sort */ 
PHP_FUNCTION(natsort) 
{ 
    php_natsort(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0); 
} 
/* }}} */