digitalmars.D.learn - Problem with using readln.

JV (29/29) Apr 29 2017 Hello i'm kinda new to D language and i wanted to make a simple

Adam D. Ruppe (3/7) Apr 29 2017 That shouldn't even compile... are you sure that's your actual

JV (4/11) Apr 29 2017 umm im using code blocks so far it compiled and runs i don't know

Adam D. Ruppe (3/4) Apr 29 2017 That's not necessary, it doesn't change anything.

JV (4/8) Apr 29 2017 okay?? but how do i return an int?

JV (2/7) Apr 29 2017 my bad for wrong import
Andrew Edwards (25/35) Apr 29 2017 Basically the simplest way would be:

arturg (4/7) Apr 29 2017 is there a reason you mix normal call and ufc or just some style?

JV (3/32) Apr 29 2017 I added the () at readln() got deleted when editing the code

JV (31/66) Apr 29 2017 On Sunday, 30 April 2017 at 03:13:14 UTC, JV wrote:

JV (1/6) Apr 29 2017

Ivan Kazmenko (22/26) Apr 30 2017 One way would be:

JV <jrpv100997 yahoo.com> writes:

Hello i'm kinda new to D language and i wanted to make a simple 
program
but somehow my input does no go to my if statements and just 
continues to ask for the user to input.Kindly help me

btw here is my sample code

     int func;
writeln("\t\tEnter Selection : ");
     func = readln;
     writeln(func);

     if(func == 1)
     {
         writeln("hello world");
     }
     if(func == 2)
     {
         writeln("hello world");
     }
     if(func == 3)
     {
         writeln("endtime");
     }
     if(func == 4)
     {
         writeln("hello world");
     }
     if(func == 5)
     {
         writeln("hello world");
     }

Apr 29 2017

Adam D. Ruppe <destructionator gmail.com> writes:

On Sunday, 30 April 2017 at 02:07:48 UTC, JV wrote:
     int func;
 writeln("\t\tEnter Selection : ");
     func = readln;
     writeln(func);

That shouldn't even compile... are you sure that's your actual 
code, and that it is actually building successfully?

Apr 29 2017

JV <jrpv100997 yahoo.com> writes:

On Sunday, 30 April 2017 at 03:04:49 UTC, Adam D. Ruppe wrote:
 On Sunday, 30 April 2017 at 02:07:48 UTC, JV wrote:
     int func;
 writeln("\t\tEnter Selection : ");
     func = readln;
     writeln(func);

 That shouldn't even compile... are you sure that's your actual 
 code, and that it is actually building successfully?

umm im using code blocks so far it compiled and runs i don't know 
why
btw i forgot to add () at readln while editing the post

Apr 29 2017

Adam D. Ruppe <destructionator gmail.com> writes:

On Sunday, 30 April 2017 at 03:10:25 UTC, JV wrote:
 btw i forgot to add () at readln while editing the post

That's not necessary, it doesn't change anything.

But readln without arguments returns a string, not an int.

Apr 29 2017

JV <jrpv100997 yahoo.com> writes:

On Sunday, 30 April 2017 at 03:18:04 UTC, Adam D. Ruppe wrote:
 On Sunday, 30 April 2017 at 03:10:25 UTC, JV wrote:
 btw i forgot to add () at readln while editing the post

 That's not necessary, it doesn't change anything.

 But readln without arguments returns a string, not an int.

okay?? but how do i return an int?
tried using what i found in the internet like using stdio.conv; 
to use toInt() but still shows error

Apr 29 2017

JV <jrpv100997 yahoo.com> writes:

On Sunday, 30 April 2017 at 03:20:20 UTC, JV wrote:
 On Sunday, 30 April 2017 at 03:18:04 UTC, Adam D. Ruppe wrote:
 On Sunday, 30 April 2017 at 03:10:25 UTC, JV wrote:


 okay?? but how do i return an int?
 tried using what i found in the internet like using std.conv; 
 to use toInt() but still shows error

my bad for wrong import

Apr 29 2017

Andrew Edwards <edwards.ac gmail.com> writes:

On Sunday, 30 April 2017 at 03:20:20 UTC, JV wrote:
 On Sunday, 30 April 2017 at 03:18:04 UTC, Adam D. Ruppe wrote:
 On Sunday, 30 April 2017 at 03:10:25 UTC, JV wrote:
 btw i forgot to add () at readln while editing the post

 That's not necessary, it doesn't change anything.

 But readln without arguments returns a string, not an int.

 okay?? but how do i return an int?
 tried using what i found in the internet like using stdio.conv; 
 to use toInt() but still shows error

Basically the simplest way would be:

     int val;
     readf("%d", &val);

But if you are dead set on using readln, you will need to parse 
the line to obtain the integer value. The following demonstrates:

     // Scherkl-Nielsen self-important lookup
     template Module(string moduleName)
     {
	mixin("import Module = " ~ moduleName ~ ";");
     }

     void main()
     {
         with(Module!"std.stdio: readln, writeln")
	with(Module!"std.conv: parse")
	{
             string line;
             parse!int((line = readln)).writeln;
	}
     }

Your attempt failed because there is a '\n' character sitting at 
the end of the line read in by readln. It cannot be converted to 
an integer so any attempt to do so will result in an Exception 
being thrown. As was the case with toInt.

-- Andrew

Apr 29 2017

arturg <var.spool.mail700 gmail.com> writes:

On Sunday, 30 April 2017 at 05:53:09 UTC, Andrew Edwards wrote:
             string line;
             parse!int((line = readln)).writeln;
 

is there a reason you mix normal call and ufc or just some style?
you can do this and remove some ()

(line = readln).parse!int.writeln;

Apr 29 2017

JV <jrpv100997 yahoo.com> writes:

On Sunday, 30 April 2017 at 02:07:48 UTC, JV wrote:
 Hello i'm kinda new to D language and i wanted to make a simple 
 program
 but somehow my input does no go to my if statements and just 
 continues to ask for the user to input.Kindly help me

 btw here is my sample code

     int func;
     writeln("\t\tEnter Selection : ");
     func = readln();
     writeln(func);

     if(func == 1)
     {
         writeln("hello world");
     }
     if(func == 2)
     {
         writeln("hello world");
     }
     if(func == 3)
     {
         writeln("endtime");
     }
     if(func == 4)
     {
         writeln("hello world");
     }
     if(func == 5)
     {
         writeln("hello world");
     }

I added the () at readln() got deleted when editing the code 
before i posted. sorry

Apr 29 2017

JV <jrpv100997 yahoo.com> writes:

On Sunday, 30 April 2017 at 03:13:14 UTC, JV wrote:
 On Sunday, 30 April 2017 at 02:07:48 UTC, JV wrote:
 Hello i'm kinda new to D language and i wanted to make a 
 simple program
 but somehow my input does no go to my if statements and just 
 continues to ask for the user to input.Kindly help me

 btw here is my sample code

     int func;
     writeln("\t\tEnter Selection : ");
     func = readln();
     writeln(func);

     if(func == 1)
     {
         writeln("hello world");
     }
     if(func == 2)
     {
         writeln("hello world");
     }
     if(func == 3)
     {
         writeln("endtime");
     }
     if(func == 4)
     {
         writeln("hello world");
     }
     if(func == 5)
     {
         writeln("hello world");
     }

 I added the () at readln() got deleted when editing the code 
 before i posted. sorry

On Sunday, 30 April 2017 at 03:13:14 UTC, JV wrote:
     int func;
     writeln("\t\tEnter Selection : ");
     func = readln;
     readln(func);

     if(func == 1)
     {
         writeln("hello world");
     }
     if(func == 2)
     {
         writeln("hello world");
     }
     if(func == 3)
     {
         writeln("endtime");
     }
     if(func == 4)
     {
         writeln("hello world");
     }
     if(func == 5)
     {
         writeln("hello world");
     }
     else
     {
     display();
     }

Mybad i posted the wrong one

Apr 29 2017

JV <jrpv100997 yahoo.com> writes:

On Sunday, 30 April 2017 at 03:18:39 UTC, JV wrote:
 On Sunday, 30 April 2017 at 03:13:14 UTC, JV wrote:
 On Sunday, 30 April 2017 at 02:07:48 UTC, JV wrote:


     int func;
     writeln("\t\tEnter Selection : ");
     readln(func);

Apr 29 2017

Ivan Kazmenko <gassa mail.ru> writes:

On Sunday, 30 April 2017 at 02:07:48 UTC, JV wrote:
 Hello i'm kinda new to D language and i wanted to make a simple 
 program
 but somehow my input does no go to my if statements and just 
 continues to ask for the user to input.Kindly help me

One way would be:

     import std.stdio;
     int x;
     readf (" %s", &x);

The "%s" means "default format for the type", which is I believe 
"%d" (decimal) for the int type.  The space before "%s" is to 
skip all whitespace before the actual input, it will matter when 
you read your second integer:

     readf ("%s%s", &x, &y); // error, got space for y instead of 
a digit
     readf ("%s %s", &x, &y); // ok

Another way is:

     import std.conv, std.stdio, std.string;
     int x = readln.strip.to!int;

Here, we read the line with readln, strip the trailing whitespace 
with strip, and convert the resulting string to an int with 
to!int.

Also, you might want to look at the corresponding chapter in Ali 
Cehreli's book:
http://ddili.org/ders/d.en/input.html

Ivan Kazmenko.

Apr 30 2017

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digitalmars.D.learn - Problem with using readln.