C Programming Language :: can any bdy help me


	can any bdy help me hai, i have developed a c-code to push integers into a stack (an array). in the program there are three inputs which has to be given through keyboard. the inputs are "choice", "option","S_R_NO" and "i" all are defined as "int". now when the inputs given are int type the program behaviour is as required. but when the input given are char type the program is executing infinite loop.i could not understand this behaviour and i am unable to start. the code is developed on turbo-c and it is executiable. can any one help me in finnding the bug and tell me the better way of doing. --------------------------------------------------------------------------- ------- #include<stdio.h> #include<conio.h> #include<iostream.h> #define SIZE 6 int top=-1; void main() { void push(int); int stack[SIZE], stk_ptr; int choice; int S_R_NO,option; stk_ptr=stack; start: //here it starts clrscr(); printf("\nEnter 1 to continue: "); scanf("%d",&choice); if(choice==1) { push(stk_ptr); printf("\nTo continue press 1 to exit 0:"); scanf("%d",&option); if(option==1) goto start; } else{ printf("CAUTION:WRONG CHOICE, ENTER 1 TO CONTINUE 0 TO EXIT: "); fflush(stdin); scanf("%d",&S_R_NO); if(S_R_NO==1) goto start; } end: printf("\n------END OF THE PROGRAM-----"); getch(); } / ---------------------------------------------------------------------- / void push(int stk) { register int i,j; top+=1; if(top==SIZE){ printf("\nOverflow of the stack");top-=1; } else { printf("\nEnter the element you want to push: "); scanf("%d",&i); (stk+top)=i; printf("now the stack is:"); for(j=0;j<=top;j++) printf("\nelement at <%d> is <%d>",j,(stk+j)); } } / -------------------------------------------------------------------------- - / runtime problems: 1) first round input: if a char is entered for "i" program terminating without asking for the next value of "option". 2) after first round of input: if char is given as input for any of the variables "choice", "option","S_R_NO" or "i" the program is executing infiniteloop. thaking you. regards thandra. - Hide quoted text - shanti wrote: > i have developed a c-code to push integers into a stack (an array). > in the program there are three inputs which has to be given through > keyboard. the inputs are "choice", "option","S_R_NO" and "i" all are > defined as "int". > now when the inputs given are int type the program behaviour is as > required. but when the input given are char type the program is > executing infinite loop.i could not understand this behaviour and i am > unable to start. the code is developed on turbo-c and it is > executiable. > can any one help me in finnding the bug and tell me the better way of > doing. > --------------------------------------------------------------------------- ------- > #include<stdio.h> > #include<conio.h> Non-standard and unnecessary header. > #include<iostream.h> Ditto. > #define SIZE 6 > int top=-1; Global variable for stack index: bad idea. Keep it local to `main` and have `push` take an extra parameter. Later when you know about `struct` you'll be able to keep the index and the stack (and the size) all together. > void main() The portable return type for `main` is `int`. > { > void push(int); Usual style is to have function declarations outside functions. > int stack[SIZE], stk_ptr; > int choice; > int S_R_NO,option; All these uninitialised variables make me nervous. > stk_ptr=stack; > start: //here it starts You don't need labels-and-gotos for this; that's what a `while` loop is `for`. One so rarely needs a `goto` in C that a good rule of thumb is `never use goto`; eventually you will discover circumstances where it's the preferred construct. Eventually. > clrscr(); Non-standard, unnecessary, and IMAO unforgivable here. > printf("\nEnter 1 to continue: "); > scanf("%d",&choice); There's now stuff in the input stream -- at least a newline. What do you plan to do if the user doesn't input a digit? Why enter /1/ to continue -- instead of `y`, say? And why "continue" when we haven't really started yet? > if(choice==1) { > push(stk_ptr); > printf("\nTo continue press 1 to exit 0:"); > scanf("%d",&option); > if(option==1) goto start; See above. > } > else{ > printf("CAUTION:WRONG CHOICE, ENTER 1 TO CONTINUE 0 TO EXIT: > "); DON'T SHOUT AT ME, YOU STUPID MACHINE. Um. If you weren't going to let me not-continue, why did you offer me a choice in the first place? > fflush(stdin); It's undefined behaviour to fflush an input stream. Don't do that. (You want to eat characters until a newline, as a best approximation.) > scanf("%d",&S_R_NO); > if(S_R_NO==1) goto start; > } > end: > printf("\n------END OF THE PROGRAM-----"); DON'T SHOUT AT ME, YOU STUPID MACHINE. You say that, but ... > getch(); ... means that it /isn't/ the end. > } > / > ---------------------------------------------------------------------- > / > void push(int stk) Thr's n shrtg f vwls n snt. Call it `stack`. > { > register int i,j; `register` isn't terribly useful here. > top+=1; > if(top==SIZE){ printf("\nOverflow of the stack");top-=1; } > else { printf("\nEnter the element you want to push: "); `value` is better than `element`. (Usually `element` refers to the position in the stack, but that's not what you're asking for.) > scanf("%d",&i); See above. > (stk+top)=i; Um, this is idiomatically written `stk[top] = i;`. Why are you using the `(stk+top)` form? > printf("now the stack is:"); > for(j=0;j<=top;j++) > printf("\nelement at <%d> is <%d>",j,(stk+j)); (indent) (ditto) > } > } > / > -------------------------------------------------------------------------- - > / > runtime problems: > 1) first round input: if a char is entered for "i" program terminating > without asking for the next value of "option". > 2) after first round of input: if char is given as input for any of > the variables "choice", "option","S_R_NO" or "i" the program is > executing infiniteloop. Yes. You don't check for these possibilities, so when they happen, things go badly. -- "We are on the brink of a new era, if only --" /The Beiderbeck Affair/ Hewlett-Packard Limited registered office: Cain Road, Bracknell, registered no: 690597 England Berks RG12 1HN Chris Dollin <chris.dol@hp.com> wrote: > shanti wrote: > > int stack[SIZE], stk_ptr; > > int choice; > > int S_R_NO,option; > All these uninitialised variables make me nervous. I'm not sure what one would initialize choice and option to; from their names alone it would seem to be clear that they are intended to store input from the user; my religion indicates that initialization is therefore optional at best. (S_R_NO, on the other hand, might be profitably initialized, although the question of "to what" is not easy to answer without deciphering its very poor name.) > DON'T SHOUT AT ME, YOU STUPID MACHINE. My Commodore 64 shouted at me a lot, and was only pacified by magical incantations such as "LOAD , 8, 1" (or some such nonsense) :-) > Um. If you weren't going to let me not-continue, why did you > offer me a choice in the first place? For the same reason that users always got the option to "abort, retry, fail" no matter how much the real choices might have been "fail, fail, fail"... -- C. Benson Manica \| I should* know what I'm talking about - if I cbmanica(at)gmail.com \| don't, I need to know. Flames welcome. "Chris Dollin" writes: > Um. If you weren't going to let me not-continue, why did you > offer me a choice in the first place? He may have interned at Microsoft. They are experts at promising things that won't happen. Press "Cancel" on a download for example. - Hide quoted text - shanti wrote: > i have developed a c-code to push integers into a stack (an array). > in the program there are three inputs which has to be given through > keyboard. the inputs are "choice", "option","S_R_NO" and "i" all are > defined as "int". > now when the inputs given are int type the program behaviour is as > required. but when the input given are char type the program is > executing infinite loop.i could not understand this behaviour and i > am unable to start. the code is developed on turbo-c and it is > executiable. > can any one help me in finnding the bug and tell me the better way of > doing. > ------------------------------------------------------------------- > #include<stdio.h> This is OK > #include<conio.h> > #include<iostream.h> These don't exist in standard C. You would also be better off inserting spaces, as "#include <stdio.h>". Thus no answer is available here, where we deals solely with standard C as described in the C standard. Look for some newsgroup with Borland or Turbo in its name. Or, better, look for an up-to-date compiler. -- <http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.txt> <http://www.securityfocus.com/columnists/423> <http://www.aaxnet.com/editor/edit043.html> <http://kadaitcha.cx/vista/dogsbreakfast/index.html> cbfalconer at maineline dot net -- Posted via a free Usenet account from http://www.teranews.com On 31 May, 11:53, shanti <prasanth.than@gmail.com> wrote: > hai, > i have developed a c-code to push integers into a stack (an array). > in the program there are three inputs which has to be given through > keyboard. the inputs are "choice", "option","S_R_NO" and "i" all are > defined as "int". > now when the inputs given are int type the program behaviour is as > required. but when the input given are char type the program is > executing infinite loop.i could not understand this behaviour and i am > unable to start. the code is developed on turbo-c and it is > executiable. > can any one help me in finnding the bug and tell me the better way of > doing. Well, you could start by reading the FAQ - http://c-faq.com/stdio/scanfprobs.html would probably be a good start. Reading a decent book on C coding (or coding in general, actually) would also be useful. > --------------------------------------------------------------------------- ------- > #include<stdio.h> OK > #include<conio.h> > #include<iostream.h> Non-standard and not really necessary, as far as I can tell. > #define SIZE 6 > int top=-1; > void main() the standard says otherwise. > { > void push(int); > int stack[SIZE], stk_ptr; > int choice; > int S_R_NO,option; > stk_ptr=stack; > start: //here it starts It's better to use "/.../" for comments. Many compilers don't accept this form, and it's poor for cutting and pasting from newsgroup posts. > clrscr(); I will assume this clears the screen. It's not > printf("\nEnter 1 to continue: "); > scanf("%d",&choice); You don't check the return value of scanf() - a Bad Thing. What will scanf do with non-numeric input? (Hint: probably not what you want). Read the FAQ. > if(choice==1) { > push(stk_ptr); > printf("\nTo continue press 1 to exit 0:"); > scanf("%d",&option); > if(option==1) goto start; "Any references to Goto (an obscure Japanese admiral) are obscene, unfit for your eyes and anyway don't mean what you think they do - delete them" (notes on the Algol manual from a university course in the 1970s). You almost never need a goto in C. > } > else{ > printf("CAUTION:WRONG CHOICE, ENTER 1 TO CONTINUE 0 TO EXIT: > "); > fflush(stdin); According to the standard, this is meaningless. > scanf("%d",&S_R_NO); Same comments as before about scanf(). > if(S_R_NO==1) goto start; > } > end: As far as I can see you never use this label. > printf("\n------END OF THE PROGRAM-----"); > getch(); > } Your formatting (indentation) is appalling. Don't you have a tool to do it, perhaps in your editor? - Hide quoted text - > / > ---------------------------------------------------------------------- > / > void push(int stk) > { > register int i,j; > top+=1; > if(top==SIZE){ printf("\nOverflow of the stack");top-=1; } > else { printf("\nEnter the element you want to push: "); > scanf("%d",&i); > (stk+top)=i; > printf("now the stack is:"); > for(j=0;j<=top;j++) > printf("\nelement at <%d> is <%d>",j,(stk+j)); > }} Are you kidding? 1) The formatting of the code is awful 2) the mixing of interaction with the user and manipulation of the stack is hopeless. The natural prototype for push() in your code is much more likely to be int push(int stack, int value); /* return 1 for success, 0 for failure (overflow) / > / > -------------------------------------------------------------------------- - > */ > runtime problems: > 1) first round input: if a char is entered for "i" program terminating > without asking for the next value of "option". Read the FAQ - and perhaps the standard - and find out what scanf() would return in this case. > 2) after first round of input: if char is given as input for any of > the variables "choice", "option","S_R_NO" or "i" the program is > executing infiniteloop. Similarly. Use something other than scanf() for a start... In your position, I'd start by writing code to maintain a stack - with push and pop operations, and write a simple non-interactive testcase to exercise it, the only I/O would be a few printf() statements to show the state of the stack at various points in the code. Once I'd done that, I'd look at how to add some interactive code to my testcase.