/*  Simple program to .... */
#include  <stdio.h>

int main ( )
{
  int row, column;
  int size;

  printf("Enter the size: ");
  scanf("%d", &size);

  row = 1;
  while (row <= size) {
    column = 1;
    while (column <= size) {
      printf("* ");
      column++;
    } /* end while (column... */
    printf("\n");
    row++;
  } /* end while (row... */

  return 0;  /* 0 indicates program ended successfully */
}  /* end main */

2) Write a sentinel-controlled program to average scores using a "do-while" loop.

/* Fig. 4.7: fig04_07.c     Counting letter grades */

#include <stdio.h>



int main() {    /* function main begins program execution */

   int grade;      /* one grade */

   int aCount = 0; /* number of As */

   int bCount = 0; /* number of Bs */

   int cCount = 0; /* number of Cs */

   int dCount = 0; /* number of Ds */

   int fCount = 0; /* number of Fs */



   printf(  "Enter the letter grades.\n"  );

   printf(  "Enter the EOF character to end input.\n"  );



   /* loop until user types end-of-file key sequence */

   while ( ( grade = getchar() ) != EOF ) {

      

      /* determine which grade was input */

      switch ( grade ) { /* switch nested in while */



         case 'A': /* grade was uppercase A */

         case 'a': /* or lowercase a */

            ++aCount; /* increment aCount */

            break; /* necessary to exit switch */



         case 'B': /* grade was uppercase B */

         case 'b': /* or lowercase b */

            ++bCount; /* increment bCount */

            break; /* exit switch */



         case 'C': /* grade was uppercase C */

         case 'c': /* or lowercase c */

            ++cCount; /* increment cCount */

            break; /* exit switch */



         case 'D': /* grade was uppercase D */

         case 'd': /* or lowercase d */

            ++dCount; /* increment dCount */

            break; /* exit switch */



         case 'F': /* grade was uppercase F */

         case 'f': /* or lowercase f */

            ++fCount; /* increment fCount */

            break; /* exit switch */



         case '\n': /* ignore newlines, */

         case '\t': /* tabs, */

         case ' ':  /* and spaces in input */

            break; /* exit switch */



         default: /* catch all other characters */

            printf( "Incorrect letter grade entered." ); 

            printf( " Enter a new grade.\n" ); 

            break; /* optional; will exit switch anyway */

      } /* end switch */

   

   } /* end while */



   /* output summary of results */

   printf( "\nTotals for each letter grade are:\n" );

   printf( "A: %d\n", aCount ); /* display number of A grades */

   printf( "B: %d\n", bCount ); /* display number of B grades */

   printf( "C: %d\n", cCount ); /* display number of C grades */

   printf( "D: %d\n", dCount ); /* display number of D grades */

   printf( "F: %d\n", fCount ); /* display number of F grades */



   return 0; /* indicate program ended successfully */



} /* end function main */