fig03_08.c

C程序设计经典教程第5版程序示例,比较适合初级c语言的学生

/* Fig. 3.8: fig03_08.c
   Class average program with sentinel-controlled repetition */
#include <stdio.h>

/* function main begins program execution */
int main( void )
{
   int counter; /* number of grades entered */
   int grade;   /* grade value */
   int total;   /* sum of grades */

   float average; /* number with decimal point for average */
   
   /* initialization phase */
   total = 0;   /* initialize total */
   counter = 0; /* initialize loop counter */
   
   /* processing phase */
   /* get first grade from user */
   printf( "Enter grade, -1 to end: " ); /* prompt for input */
   scanf( "%d", &grade );                /* read grade from user */
   
   /* loop while sentinel value not yet read from user */
   while ( grade != -1 ) {
      total = total + grade; /* add grade to total */
      counter = counter + 1; /* increment counter */
      
      /* get next grade from user */
      printf( "Enter grade, -1 to end: " ); /* prompt for input */
      scanf("%d", &grade);                  /* read next grade */
   } /* end while */

   /* termination phase */
   /* if user entered at least one grade */
   if ( counter != 0 ) {

      /* calculate average of all grades entered */
      average = ( float ) total / counter; /* avoid truncation */

      /* display average with two digits of precision */
      printf( "Class average is %.2f\n", average );   
   } /* end if */   
   else { /* if no grades were entered, output message */
      printf( "No grades were entered\n" );
   } /* end else */

   return 0; /* indicate program ended successfully */

} /* end function main */



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