C + + do not use variables to find the implementation method of string length strlen function _c language

This article illustrates the implementation method of C + + not using variables to find the strlen function of string length. Share to everyone for your reference. The implementation methods are as follows:

1, strlen source code to achieve:

size_t strlen (const char *str)
//strlen does not make a memory illegal judgment, if it is null, will core.
{
    const char *eos=str;
    while (*eos++);
    return (eos-str-1);
}

2, common face questions will require not to use additional variables to achieve the Strlen function:

Achieve one:

int strlen (const char *str)
{
   if (' ==*str ') return
       0;
   else return
       strlen (str+1) +1;
}

Realize two:

int strlen (const char *str)
{return
   *str? ( Strlen (str+1) +1): 0;
}

I hope this article will help you with the C + + program design.