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how to eliminate all keyboard inputs accept a certain range
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hi guys and gals, just a young padawan learner trying to write this poker program from scratch. i know their are programs out their but nothing like the one you write your self. Im trying to have my program read in the number of players from the keyboard input. I have eliminated all the numbers i dont want. but what if someone enters in letters or special characters how do i eliminate all the keyboard functions except my small range of numbers. My first guess was to have the 1-20 in ascii and all other ascii codes would be a bad input didnt know how to write it. this is probaly elimentary but im stomped heres the little code i have wrote. numofplayers is a int i made it a char but that didnt work. also i hear goto statements are bad how could i avoid the first two goto statements in this elimentary program. thanks i appreciate any help.
<< moderator edit: added [code][/code] tags >>
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In general you can do something like this although you should drop the deprecated headers for the std headers.
This will grab input from the keyboard and junk a non-integer input and wait for more input. If an int is entered then code proceeds past the comment.
It is also possible to validate input like this to a range of ints something like this (from a previous thread I participated in).....
Although often I will make a validate function ifthe expression gets complicated and just call that function there instead.
C Syntax (Toggle Plain Text)
It is also possible to validate input like this to a range of ints something like this (from a previous thread I participated in).....
C Syntax (Toggle Plain Text)
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Join Date: Jun 2004
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mmhm, there are a few ways of doing this. stoned_coder listed one way. I am in a hurry and have to go... this is what I did. I suggested using atoi... converting a string to an integer and then using your if statment... there is also a function called kbhit... but I dont have time to go into details.
as far as removing goto's you should used structured programming. reading up on how to do function calls would be a good start. I removed the first call to goto_xxx by changing the goto to a loop (do until loop)... you should also read up on the diffrent type of loops..
for loop/ do loop / while loop...
best of luck... gota run!
<< moderator edit: added [code][/code] tags and indenting >>
as far as removing goto's you should used structured programming. reading up on how to do function calls would be a good start. I removed the first call to goto_xxx by changing the goto to a loop (do until loop)... you should also read up on the diffrent type of loops..
for loop/ do loop / while loop...
best of luck... gota run!
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hey stoned coder got a couple of questions. first thanks for responding its always hard to find good help. thanks to binary mayhem as well. one day when i am a gozillionare i will remember you guys. but what does the ! point in the while statement do. i know cin grabs the input stores it in input. what does the login on the ! point mean. what does cerr do. the .clear() is a function im guessing that is a built in function in the stanard library what does that do. if you could elaborate on this hold line i would be much abliged cin.ignore(numeric_limits<streamsize>::max(),'\n');
i just learn funny. i have to do a line by line every word thing. i pick up really fast if explained. kinda wierd i guess. thanks binary mayhem thanks you know i understand that and i had found that atoi keyword but i didnt think to use that thanks. while i got you guys attention do you guys ever write to the an example would be much abliged and you know how you give variables and amount and it stores that in memory. how do you erase all the amounts or do the variables just get erased at the end of the program. thanks.
bruce wayne
i just learn funny. i have to do a line by line every word thing. i pick up really fast if explained. kinda wierd i guess. thanks binary mayhem thanks you know i understand that and i had found that atoi keyword but i didnt think to use that thanks. while i got you guys attention do you guys ever write to the an example would be much abliged and you know how you give variables and amount and it stores that in memory. how do you erase all the amounts or do the variables just get erased at the end of the program. thanks.
bruce wayne
binary mayhem i put in what you wrote with the loop. if i put in a letter it quits the program. when atoi converts it to an int does it convert it to the decimal number of the letter or ascii. when a letter is put in i probaly want to have it loop back again. what about this you think.
<< moderator edit: added code tags: [code][/code] >>
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Associated with cin are a set of error flags. The important one at this time is the fail flag. If the cin>>input goes to plan and grabs an int then this expression returns true through the overloaded operator void* (prolly too much info at this stage). operator ! is the not operator. It makes true flase and false true. Thats about it. cerr is like cout. its basically an error stream thats attatched to the console, so you could have used cout there but I like cerr as it can be easily rerouted to a logfile and cout left pointing to the console screen. If the cin>>input doesnt go to plan then the fail flag gets set and this causes the expression to return false. Then we enter into the block where firstly an error message is printed then the garbage in the stream is extracted. This is a two stage process. As you remember to get here the fail flag is set, but all ops on a failed stream are not garaunteed. So firstly we use a member function called clear to set the error flags back to good. Then we use another member function ignore to remove the detritus from the stream. That expression removes as many chars as possible or up to the next newline.
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binary mayhem i put in what you wrote with the loop. if i put in a letter it quits the program. when atoi converts it to an int does it convert it to the decimal number of the letter or ascii. when a letter is put in i probaly want to have it loop back again. what about this you think.
I put the if (numofplayers==0) return 0; to quit the app. (what if the person does not want to play?) what should have been does was compared it to -1 so it would quit the app and zero would have just reported an error.
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