md5 - PHP如何把字符串hash成10进制数字
md5这种方法都是哈希成一个字符+数字的字符串，但是现在我需要把一个字符串哈希成10进制数字，有没有什么算法可以实现的，或者可以吧md5的结果转换成10进制的
回复内容：
md5这种方法都是哈希成一个字符+数字的字符串，但是现在我需要把一个字符串哈希成10进制数字，有没有什么算法可以实现的，或者可以吧md5的结果转换成10进制的
一般情况而言需要做字符串到十进制数字的转换可以用 crc32() 函数 ...
这个函数的优点是快 ... 在我的知识范围内这应该是 php 内置最快的哈希函数 ...
缺点是操作系统依赖 ... 不同操作系统的 crc32() 函数会产生不一样的值 ...
至于把 md5() 的结果转化成十进制 ... 用 hexdec() 显然是不靠谱的 ... 原因如楼上所说不赘述 ...
这里我们用到另外一个更加灵活的进制转换函数 base_convert() ...
这个函数的好处是返回 string ... 也就不存在溢出的问题了 ...
示例代码如下 ...
<?php echo base_convert( md5( 'something' ), 16, 10 ); // 89699910832403552662426604448206446062
hash 成 10进制，就成 big number
你可以用php的hexdec函数，把md5的结果分段转，因为hexdec最大只能转0x7fffffff，再大就变成float了。
另外，你不一定非要用md5，因为md5的结果是128bit的，php语言本身无法直接保存这么大的十进制数。可以参考sdbmhash、jshash、或者C++ STL里对字符串的哈希自己实现一个，例如这个是python版的sdbmhash
def sdbm_hash_string(str):
h = 0
m = (1 <p>最后顺便说一下，不要试图把md5结果拆成几段然后XOR之类的，效果不如直接取最后几个字节。</p>
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