EOF AND GETCHAR to end loop

Question

I'm new in C programing language . I have a question how can I end loop in windows.

#include<stdio.h>
#include<conio.h>

int main() {
    printf("enter ur palindrome");
    int i[100], c, d = 0, n = 0;

    c = getchar();
    while (c != '\n') {
        i[d] = c;
        d++;
    }
loop:
    while (d != 0) {
        if ((i[0 + n] != i[d - n])) {
            n++;
            goto loop;
        }

        printf("this is not a palindrome");

        break;
    }
    printf("this is a palindrome");

    return (0);
}

I HAVE TRIED ALMOST EVERYTHING CTRL+Z, CTRL+C, CTRL+D, REPLACING '\\n' WITH EOF and many more thing. Nothing worked for me. I'm using CodeBlocks on Windows 10. Is there some other way of writing such type of program other then getchar and eof.

Answer 1

you probably want to take a look at this section again

c=getchar();
  while(c!= '\n') // Value of c never altered, hence it'll never break
  { i[d]=c;
  d++;
  }

and yes, the other loop

  loop: // not required
  while (  d!=0  ) // can't see change in d within this body, is it n ?
  {
     if((i[0+n] != i[d-n]))
     {
      n++; 
      goto loop; // not required
      continue; //will do
     }
     printf("this is not a palindrome");
     break;
 }

and you'd actually get an extra message saying

this is a palindrome

after printing

this is a not palindrome

which I suppose is not what you want.

Answer 2

In that loop you need to again read next character so need to add getchar() in that loop

  c=getchar();
  while(c!= '\n')
  {
  i[d]=c;
  d++;
  c=getchar();
  }

Answer 3

Here's a different way to write that piece of code

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


int main()
{
    char *word;
    int i;
    int n;

    printf( "enter ur palindrome" );
    scanf("%[^\n]", word);                     // reads input all the way to the new line
    n = strlen( word );

    for ( i = 0; i < n; i++ ) {
        if ( word[ i ] != word[ n-1 - i ] ) {
            break; /* for */
        }
    }
    if ( i == n ) {
        printf( "This is a palindrome");
    } else {
        printf( "This is not a palindrome" );
    }

    return 0;
}

Answer 4

Rather than using goto , use continue; to repeat the loop.

However, there are a number of other problems with the posted code.

The array `int i[100]` is never terminated with a NUL byte ('\0')
An array of char not int should be used.
this loop: `while (d != 0) will never exit, 
    because (if the loop is ever entered)
    the `d` variable is never changed within the loop

Here is my suggested code:

caveat: not thoroughly tested

#include <stdio.h>
//#include<conio.h> <-- not used, so do not include
#include <string.h>

#define MAX_LENGTH (100)

int main( void )
{
    int d;
    int n;
    char i[MAX_LENGTH];

    printf("enter ur palindrome\n"); // <-- \n so will immediately print

    if ( NULL != fgets( i, MAX_LENGTH, stdin ) )
    {
        if( strlen( "\n" ) < strlen( i ) )
        { // then, some string entered

            // remove any trailing '\n'
            char *newline = strstr( i, "\n" );
            if( newline )
            { // then '\n' found
                *newline = '\0';
            } // end if

            d = strlen( i );
            for( n=0; (d-n) >= n; n++ )
            {

                if( i[0 + n] != i[d - n] )
                { // then no match
                    printf("this is not a palindrome");
                    break;
                } // end if
            } // end for

            if( (d-n) < n )
            { // then palindrome
                printf("this is a palindrome");
            } // end if
        }

        else
        {
            printf( "nothing entered\n");
        } // end if
    } // end if

    return (0);
} // end function: main