快速strlen的问题 [英] Quick strlen question
问题描述
我来打扰你所有的另一个可能真正简单的C的问题。
I've come to bother you all with another probably really simple C question.
使用以下code:
int get_len(char *string){
printf("len: %lu\n", strlen(string));
return 0;
}
int main(){
char *x = "test";
char y[4] = {'t','e','s','t'};
get_len(x); // len: 4
get_len(y); // len: 6
return 0;
}
2的问题。为什么他们不同的,这是为什么Y 6?谢谢你们。
2 questions. Why are they different and why is y 6? Thanks guys.
编辑:对不起,我知道会解决它,我有种只是想知道发生了什么事情。因此,没有strlen的只是不停的转发,直到点碰巧找到\\ 0?此外,当我在主函数,而不是在get_len并strlen函数两者都是四是,只是一个巧合?
Sorry, I know what would fix it, I kind of just wanted to understand what was going on. So does strlen just keep forwarding the point till it happens to find a \0? Also when I did strlen in the main function instead of in the get_len function both were 4. Was that just a coincidence?
推荐答案
是
是不是空终止。 的strlen()
直到碰到一个空字符计数的字符。你的月份找到一个6之后,但它可以是任何数量。试试这个:
y
is not null-terminated. strlen()
counts characters until it hits a null character. Yours happened to find one after 6, but it could be any number. Try this:
烧焦Y [] = {'T','E','S','T','\\ 0'};
下面就是的实现的strlen()
可能看起来像(从我的头顶 - 没有我的K&安培; R书方便,但我相信,有鉴于有实现):
Here's what an implementation of strlen()
might look like (off the top of my head -- don't have my K&R book handy, but I believe there's an implementation given there):
size_t strlen(const char* s)
{
size_t result = 0;
while (*s++) ++result;
return result;
}
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