Pointer to a C-String? [closed] - c++

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For an intro to CS assignment, I am writing a C++ program in Visual Studio 2010 which returns an integer and accepts a pointer to a C-string as an argument. I know that I need to make a function besides an int main to succeed, but I am not exactly sure about how to initialize a char pointer array which points to a predefined char array, if possible.
The purpose of this program is to get a comment from a user within a predefined limit then inform said user how many characters (including whitespace) that comment is.
The error is: a value of type "char" cannot be assigned to an entity of type "char *";
Here is my program that does not compile:
#include "stdafx.h"
#include <iostream>
#include <string>
#include <conio.h>
using namespace std;
//function protoype
void evalStr(char arr[]);
//variable
int length;
//main function
int main()
{
const int SIZE = 201;
char arr[SIZE];
char *str[SIZE];
cout << "Please enter a comment under " << (SIZE - 1) << " characters to calculate it's length: ";
*str = arr[SIZE];
cin.getline(arr, SIZE);
length = strlen(*str);
evalStr(arr);
system("PAUSE");
return 0;
}
//function defintion
/* get the string
count the number of characters in the string
return that number
*/
void evalStr(char arr[])
{
printf("The length of the entered comment is %d characters\n", length);
}
If there is a general method to utilizing char pointer arrays or perhaps pointers to strings, this code could be redone to return the value of the string instead of utilizing that printf statement. What all am I doing wrong?
Edit: Here is an updated version of this program that compiles, runs, and informs the user if the character limit is reached or exceeded.
// Accept a pointer to a C-string as an argument
// Utilize the length of C-string in a function.
// Return the value of the length
// Display that value in a cout statement.
#include "stdafx.h"
#include <iostream>
#include <string>
#include <conio.h>
using namespace std;
//variables
const int SIZE = 201;
int length;
char arr[SIZE];
char *str;
//main function
int main()
{
str = &arr[0];
// Size - 1 to leave room for the NULL character
cout << "Please enter a comment under " << (SIZE - 1) << " characters to calculate it's length: ";
cin.getline(arr, SIZE);
length = strlen(str);
if (length == (SIZE - 1))
{
cout << "Your statement has reached or exceeded the maximum value of "
<< length << " characters long.\n";
}
else
{
cout << "Your statement is ";
cout << length << " characters long.\n";
}
system("PAUSE");
return 0;
}
//function defintion
/* get the string
count the number of characters in the string
return that number
*/
int countChars(int)
{
length = strlen(str);
return length;
}

Answer 1

Let's talk about what is happening in main instead:
int main()
{
Okay, so you're going to have strings of 201 characters. Seems reasonable.
const int SIZE = 201;
And you've declared an array of 201 characters:
char arr[SIZE];
And now you declare an array of 201 pointers to characters. I'm not sure why you would want to do that. I suspect you think this does something other than what it actually does:
char *str[SIZE];
This is reasonable (except "it's" means "it is", but you want the possessive version, "its"):
cout << "Please enter a comment under " << (SIZE - 1) << " characters to calculate it's length: ";
This assigns the 201st character to the first character pointer in your array of char pointers. This is an error because:
arrays are zero-indexed, so the 201st character (when you start counting at zero) is beyond the end of the array.
you haven't initialized the memory in arr to anything yet.
you're assigning a char to a char *.
So, given the above I'm not sure why you're doing this:
*str = arr[SIZE];
This looks reasonable:
cin.getline(arr, SIZE);
This is an error because str doesn't point to memory that contains a valid string at this point.
length = strlen(*str);

Answer 2

When you "point to a string", actually you point to the first character of the string. The end of the string can be found by looking at successive memory locations until you find a location containing a null byte. So your code should be:
char *str; // can point at a character
// ....
str = &arr[0]; // point to the first character of arr
// ....
length = strlen(str);