Example of struct in book causing a headache

This could help Flush the input buffer

Code:

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    84    if (scanf("%d", &nfl.points) != 1)
    85            printf("Please try again\n");
    86
    87    while ((ch = getchar()) != '\n' && ch != EOF);
    88      {
    89    if (scanf("%d", &nfl.yards) != 1)
    90            printf("Please try again\n");
    91      }

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-reading what getchar does I am puzzled how this while loop solved my problems. I declared int ch; in program also. This loop seems to clear out string from previous if statement. Can someone explain why this works now? I am using link you posted above but still confused.

Well I am guessing it just verifies there is data in stdin and overwrites those contents??

-Also how could I add code to make user enter a correct number instead of using printf and exiting with no valid input?

And more importantly utilize the quotee below:

Quote:

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fgets( buff, BUFSIZ, stdin );
Then validate buff in whatever way you choose, and copy the data to it's final destination.

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Do I just assign buff = nfl.points and then see ifisdigit?

if user pesses something like
qw<ENTER>
scanf("&#37;d"...
will not be able to read anything from the stream leaving 3 chars there
'q' , 'w' , '\n'

while loop added just reads all chars till it encounters \n - leaving stdin empty

so probably your alltogether loop should be

Code:

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while(scanf("%d",&nfl.points) != 1)
{
  /* clean the stdin */
  int ch;
  while ((ch = getchar()) != '\n' && ch != EOF);

  /* and try again */

  printf("Please try again\n");
}

/* succesfully read nfl.points number - could continue*/

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Quote:

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Do I just assign buff = nfl.points and then see ifisdigit?

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no, if you want to use fgets approch - it will be like

Code:

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char buffer[BUFSIZ];
char* res;
while((res = fgets(buffer,sizeof buffer, stdin)) != NULL)
{
  if(sscanf(buffer, "%d" , &nfl.points) != 1) /* we can use strtol to make more carefull testing of the user input */
  {
      /* successfully read number */
      break;
  }
  /* line format was incorrect */
  printf("Please try again\n");
}

if(res == NULL)
{
  /* fgets failed - probably EOF riched - need to abort */
  return -1;
}

/* successfully read number - we can continue */

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I will add to my program both methods you explained. Thanks for the help!

Works very well. Thanks again!

Quote:

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Originally Posted by cjohnman

I will add to my program both methods you explained. Thanks for the help!

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do not mix fgets and scanf in the same program - stick to one method - or read everything with fgets and then convert

or use scanf - without need for convert...

mixing them could bring unexpected bugs in your code due to scanf leaving \n in stdin and next fgets reading it instead of the next string...

Should this be ok?

Code:

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    95    printf("Please enter total points\n");
    96    while(scanf("%d",&nfl.points) != 1)
    97    {
    98      /* clean the stdin */
    99      while ((ch = getchar()) != '\n' && ch != EOF);
    100
    101      /* and try again */
    102      printf("Please try again\n");
    103    }
    104
    105    printf("Please enter total yards\n");
    106      while(scanf("%d",&nfl.yards) != 1)
    107          {
    108            /* clean the stdin */
    109            while ((ch = getchar()) != '\n' && ch != EOF);
    110
    111            /* and try again */
    112            printf("Please try again\n");
    113          }

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