Function to check whether the input is composed ONLY of alphabet/space

I got this code. (It's more of a test code since I will use this as a function for my address book program)
This code is supposed to ask the user to input characters at most 20 and they should only be composed of alphabets/spaces..

Code:

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

int main()
{   
   char addressbook[6][30][0];
   int current_record = 0, length, i=0;
   int address_count = 0;
   current_record = address_count-1; //variable for the current entry
    
    do{
    printf("Enter the first name:"); //asks the user to input the first name of the entry
    scanf("%s", addressbook[0][current_record]);
    length = strlen(addressbook[0][current_record]); //gets the length of the input (should be less than 20)
    for(i=0; i<=20; i++){
        if(isalpha(addressbook[0][current_record][i])||addressbook[0][current_record][i]==' ')
        { //checks if the input characters in first name are alphabets/a space
            break; //
        } //exits once it sees that the characters are composed of alphabets/space
        else {
        printf("You can only use alphabets and space and a maximum of 20 characters. Input again."); //puts a message that prompts the user to enter alphabets/space alone
        } //end else    
    } // end for
    } //end do
    while(length<20)
    
    
    return 0;
}

I have removed the error from the main code but there's still this lingering error in the return part.

syntax error before 'return'.

It won't compile. Help me see what's wrong with the code?

Code:

do{
...
}while(...) ;

yay. thanks. ) now it's working. although it loops even though I've typed only alphabets and spaces. Do you know how to stop it looping after getting the desired input?

Boy, where to start. You got this from somewhere else? If so, my advice is to burn it and put together your own solution.

Code:

char addressbook[6][30][0]

What the heck is that supposed to do? Apparently create a 3D array but have the 3rd dimension of zero elements.
Which leads to more nonsense:

Code:

if(isalpha(addressbook[0][current_record][i])||addressbook[0][current_record][i]==' ')

The rest of the looping and logic makes no sense either given what you want to accomplish. The do/while loop will only end when length >= 20. The for loop is broken when 'presumably' the first alphabetic/space character is seen, otherwise it will print an error and continue looping. (I say presumably because of the zero-length 3rd dimension).

Also, some minor things:
Magic Numbers are bad
and
See here for excellent brief on good commenting

In future, please don't open a new topic just because you can't wait for an answer.
Stick to one thread.

Bye, Andreas

Agreed - use the other thread, as AndiPersti points out.
Closed.