与scanf（％ms）一起使用strlen

Question

Is it possible to use strlen() over a dynamically allocated string?

FOR EXAMPLE :

#include <stdio.h>
#include <string.h>

int main ()
{
  char *input=NULL;
  printf ("Enter a sentence: ");
  scanf("%ms", &input);
  //Is this legit?
  printf ("The sentence entered is %u characters long.\n",(unsigned)strlen(input));
  return 0;
}

Answer 1

You can use strlen() on any sequence of char s ended by a '\\0' , the null-character aka NUL ^*1 , which in fact equals 0 .

It does not matter how the memory has been allocated.

So yes, this also applies to " dynamically allocated " memory.

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^{*1: Not be mixed up with NULL , which is the null-pointer constant.}