c语言求字符串长度在自定义函数中实现并以#号结束

long  length(char c[]);
#include <stdio.h>
int main(int argc, const char * argv[]) {
    long len,i;
    char str[30];
    for (i=0; i<30; i++) {
        scanf("%c",&str[i]);
    }
    len=length(str);
    printf("string has %ld characters.",len);
    return 0;
}
long  length(char c[])
{
    char  *p=c;
    while (*p!='#') {
        p++;
    }
    return p-c;
}

output:

123vgvcuvcuiwbcvvugvujkbb jb#
string has 28 characters.Program ended with exit code: 0