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

#include
main()
{
    int mystrlen(char *);
    char str[100];
    char *p;
    p=str;
    printf("Enter the string..?\n");
    scanf("%s",p);
    int x=mystrlen(p);
    printf("Length of string is=%d\n",x);


}
int mystrlen(char *p)
{
    int c=0;
    while(*p!='\0')
    {
        c++;
        *p++;
    }
    return(c);
}

simple code to understand