Hi everyone! I'm trying to do error handling (with the try block) and when I give a wrong value to the variable (it is an integer and I give a non-number value), then It doesn't let me re get input. The code:


int x;

bool not_accepted = false;

while (!not_accepted) {

    try {

        write("x: ");

        readf("%d\n", x);

        not_accepted = true;

} catch (Exception msg) {

        writeln("Please give a right coordinate");

    }

On 8/19/20 1:44 PM, Flade wrote:
> Hi everyone! I'm trying to do error handling (with the try block) and when I give a wrong value to the variable (it is an integer and I give a non-number value), then It doesn't let me re get input. The code:
> 
> 
> int x;
> 
> bool not_accepted = false;
> 
> while (!not_accepted) {
> 
>      try {
> 
>          write("x: ");
> 
>          readf("%d\n", x);
> 
>          not_accepted = true;
> 
> } catch (Exception msg) {
> 
>          writeln("Please give a right coordinate");
> 
>      }

Probably readf stops as soon as it encounters an error, meaning that your input is still present.

Try instead getting a line via readln, and then trying to read that into your expected input.

-Steve

On Wednesday, 19 August 2020 at 18:11:23 UTC, Steven Schveighoffer wrote:
> On 8/19/20 1:44 PM, Flade wrote:
>> Hi everyone! I'm trying to do error handling (with the try block) and when I give a wrong value to the variable (it is an integer and I give a non-number value), then It doesn't let me re get input. The code:
>> 
>> 
>> int x;
>> 
>> bool not_accepted = false;
>> 
>> while (!not_accepted) {
>> 
>>      try {
>> 
>>          write("x: ");
>> 
>>          readf("%d\n", x);
>> 
>>          not_accepted = true;
>> 
>> } catch (Exception msg) {
>> 
>>          writeln("Please give a right coordinate");
>> 
>>      }
>
> Probably readf stops as soon as it encounters an error, meaning that your input is still present.
>
> Try instead getting a line via readln, and then trying to read that into your expected input.
>
> -Steve

Thanks Steve! I will get the input a string then as you said and then I'll try to convert it! Thanks a lot, have a nice day!

On 8/19/20 11:46 AM, Flade wrote:

>> Try instead getting a line via readln, and then trying to read that into your expected input.
>>
>> -Steve
> 
> Thanks Steve! I will get the input a string then as you said and then I'll try to convert it! Thanks a lot, have a nice day!

In some cases clearerr() and readln() may be what is needed:

import std.stdio;

void main() {
  int x;

  bool accepted = false;

  while (!accepted) {
    try {
      write("x: ");
      readf(" %d", x);
      accepted = true;

    } catch (Exception msg) {

      writeln("Please give a right coordinate");
      stdin.clearerr();
      stdin.readln();
    }
  }

  writeln("x is ", x);
}

Note that I used " %d" because "%d/n" would not clean when nothing was input by just hitting the Enter key. A space character in the format string means "read and ignore any whitespace at this point" and I like it. :)

Also note I changed the name of the variable as 'accepted'. :)

Ali

On Thursday, 20 August 2020 at 19:13:31 UTC, Ali Çehreli wrote:
> On 8/19/20 11:46 AM, Flade wrote:
>
>> [...]
>
> In some cases clearerr() and readln() may be what is needed:
>
> import std.stdio;
>
> void main() {
>   int x;
>
>   bool accepted = false;
>
>   while (!accepted) {
>     try {
>       write("x: ");
>       readf(" %d", x);
>       accepted = true;
>
>     } catch (Exception msg) {
>
>       writeln("Please give a right coordinate");
>       stdin.clearerr();
>       stdin.readln();
>     }
>   }
>
>   writeln("x is ", x);
> }
>
> Note that I used " %d" because "%d/n" would not clean when nothing was input by just hitting the Enter key. A space character in the format string means "read and ignore any whitespace at this point" and I like it. :)
>
> Also note I changed the name of the variable as 'accepted'. :)
>
> Ali

Thanks a lot! Very useful info!!! And sorry for answering so late, I wasn't expecting someone to answer so I wasn't checking. Have a great day my friend!

On Thursday, 20 August 2020 at 19:13:31 UTC, Ali Çehreli wrote:
> On 8/19/20 11:46 AM, Flade wrote:
>
>>> [...]
>> 
>> Thanks Steve! I will get the input a string then as you said and then I'll try to convert it! Thanks a lot, have a nice day!
>
> In some cases clearerr() and readln() may be what is needed:
>
> import std.stdio;
>
> void main() {
>   int x;
>
>   bool accepted = false;
>
>   while (!accepted) {
>     try {
>       write("x: ");
>       readf(" %d", x);
>       accepted = true;
>
>     } catch (Exception msg) {
>
>       writeln("Please give a right coordinate");
>       stdin.clearerr();
>       stdin.readln();
>     }
>   }
>
>   writeln("x is ", x);
> }
>
> Note that I used " %d" because "%d/n" would not clean when nothing was input by just hitting the Enter key. A space character in the format string means "read and ignore any whitespace at this point" and I like it. :)
>
> Also note I changed the name of the variable as 'accepted'. :)
>
> Ali

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