Find the size of a string pointed by a pointer

Question

#include 

int main ()
{
    char *ptr = \"stackoverflow\"

}

Is there any way to find the length of stackoverflow pointed by ptr, a

Answer 1

if ptr length is an argument of a function it's reasonable to use pointers as a strings. we can get string length by following code:

char *ptr = "stackoverflow";
length=strlen((const char *)ptr);

And for more explanation, if string is an input string by user with variable length, we can use following code:

unsigned char *ptr;
ptr=(unsigned char *)calloc(50, sizeof(unsigned char));
scanf("%s",ptr );
length=strlen((const char *)ptr);