NULL reference

[TwOoFtEn]

So I am in school learning how to program... we just did up a little program to count the number of characters in an array. I wrote it so that it would loop, counting as it goes, and end when it hits the NULL thingy....
It does not however end when it should... and with a printf() I display the contents of each element, and they are just random characters it seems.
Any help will be appreciated :)

#include "stdafx.h"
#include <stdio.h>
 
char first[20];
char *nameptr;
 
int counter=0;
 
int main()
{
 
 
    printf("Enter your first name: ");
    scanf("%s",first);
    nameptr=first;
 
    while(nameptr!=NULL)
    {
        nameptr++;
        counter++;
        printf("pointer %c\n",nameptr);
        printf("counter %d\n",counter);
    }
 
    printf("\n%d characters in your name",counter);
 
    return 0;
 
}

[donbock]

Please use CODE tags when you post source code. If you had then I could refer to line numbers in your source code.

nameptr points to successive characters within the string. You don't want to stop when the pointer value is NULL; you want to stop when the character being pointed to is null.

Notice that NULL is different from null!

• NULL is a value that can be assigned to any pointer. Programs typically use this special pointer value to mean that the pointer variable doesn't point at anything.
• Null (or null) is a character whose value is '\0'. By definition, all well-formed strings are terminated by null.

To look at the thing being pointed at by a pointer variable you have to dereference the pointer. This is accomplished by the unary asterisk (*) operator.

For example, your first printf statement in the loop uses the %c format string (print a single character) on the nameptr variable. You want to print the character being pointed at, not the pointer value itself. For example:

printf("%c", *nameptr);

Consider a bank with many safety deposit boxes in its vault. Each box has a unique number; and that same number is stamped on the corresponding key. The box number corresponds to a pointer value. The stuff inside the box corresponds to what is being pointed at.

[TwOoFtEn]

That was great!
I learned more in the min that it took to read, than I did in 2 hours of class with my foreign speaking teach.
Very helpful, thank you!