Problems with a simple coin flipping program

This is a discussion on Problems with a simple coin flipping program within the C Programming forums, part of the General Programming Boards category; Hi, Although I have had a few years of experience with C programming, I still consider myself a fairly new ...

  1. #1
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    Problems with a simple coin flipping program

    Hi,

    Although I have had a few years of experience with C programming, I still consider myself a fairly new user. This is because my debugging skills are primitive and I still can't seem to get around simple errors.

    I was writing a code to:
    - flip a coin a 1000 times
    - display "heads" or "tails" as each flip comes up
    - count the result of each flip, and display percentages of heads and tails when its done

    Although I initially wrote another code which worked fine, I decided to simplify the code. However, I get a few errors, which I cannot seem to get around.

    Code:
    #include <stdio.h>
    #include <time.h>
    #include <stdlib.h>
    
    #define FLIPS 1000
    
    
    int main()
    {
    	int flips, result;
    	int head_count = 0;
    	float hpercent, tpercent;
    
    	srand((unsigned)time(NULL));
    
    	for(flips=0; flips<FLIPS; flips++)
    	{
    		result = rand() % 2;
    
    		if(result)
    		{
    			head_count += 1;
    			printf("Heads ");
    		}
    		else
    			printf("Tails ");
    		}
    	}
    	
    	hpercent = ((float)head_count / FLIPS) * 100;   /* The errors start here */
    	tpercent = 100.0 - hpercent;
    
    	printf("Heads: %.2f percent \n", hpercent);
    	printf("Tails: %.2f percent \n", tpercent);          /* And end here */
    
    	return(0);
    }
    These are the error messages:
    coinflip2.c:32: 'head_count' undeclared here <not in a function>
    coinflip2.c:32: initializer element is not a constant
    coinflip2.c:32: warning: data definition has no type or storage class
    coinflip2.c:33: initializer element is not a constant
    coinflip2.c:33: warning: data definition has no type or storage class
    coinflip2.c:35: parse error before string constant
    coinflip2.c:35: warning: data definition has no type or storage class
    coinflip2.c:36: parse error before string constant
    coinflip2.c:36: warning: data definition has no type or string constant

    If anybody has any suggestions, please feel free to help me out.

    Thanks,

    Thileepan

  2. #2
    C++ Witch laserlight's Avatar
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    Look out for a missing opening brace:
    Code:
    		if(result)
    		{
    			head_count += 1;
    			printf("Heads ");
    		}
    		else
    			printf("Tails ");
    		}
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  3. #3
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    omg...i can't believe i missed that!!!

    i was looking over this code for like the last hr or more....lol

    thanks a lot

    what an embarassment

  4. #4
    cas
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    You're missing an opening brace in your "else" clause.

    Looks like you're using gcc. Always use -Wall when building. More warnings will be issued, and that's a good thing. -Wall in this case might have led you to the problem, although the pertinent warning isn't completely obvious. In any case, use -Wall. I can't stress this enough.

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    Hey sorry to be a pain once again,

    But I'm not quite too familiar with the -Wall concept. Can you please elaborate or refer me to a site or tutorial that provides an overview of this.

    And yes, I'm using gcc. Dev-C++ to be exact. But I was unable to figure out how the debugging works for this program, as I have tried performing breakpoint debugging, but was unable to activate it in the editor.

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    CSharpener vart's Avatar
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    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    Hey vart,

    I was actually looking over that link you posted. I still don't know how to use the -Wall command when compiling, and what the purpose of it is.

    On the link, it just states that -Wall is a combination of such and such. Sorry, still a newbie.

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    gcc -Wall coinflip2.c -o coinflip2

    I tried that...not working...am I close?

  9. #9
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    oh wait...it works...now I just gotta put some errors in there and see what it does

    thanks

  10. #10
    C++まいる!Cをこわせ! Elysia's Avatar
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    It bumps up the warning level. The compiler will issue for warnings for more things.
    Remember that good code is code with no warnings. Broken code is code with errors.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  11. #11
    Frequently Quite Prolix dwks's Avatar
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    "-W -Wall" gives you even more warnings, and "-W -Wall -ansi -pedantic" is even better, though the latter sometimes gives you warnings in GCC's own header files.

    Also, +=1 is the same as ++.
    dwk

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    Thanks

    I've been trying to compile using Quincy 2005 (all these days, I was just using notepad and DOS with the Dev-C++ compiler) and I get the following error:

    Error: ISO C90 does not support 'long long'

    Has anyone experienced that and know a possible solution?

  13. #13
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    Actually...the Compiling is fine....it's BUILD that is giving me the problem

  14. #14
    cas
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    Error: ISO C90 does not support 'long long'
    There are two (three, if you count K&R) major revisions of the C language, commonly referred to as C90 and C99--there are also C89 and C95 but that's not especially relevant here. One of the changes that C99 made was the "long long" type, which C90 does not support. If you're using the -ansi flag with gcc, that instructs it to conform to C90 and the -pedantic flag causes gcc to be, well, pedantic.

    While it doesn't fully support C99, you can enable gcc's work-in-progress C99 support by replacing -ansi with -std=c99. This will allow "long long" to work. Different people will have different opinions on what standard to target, so it's really up to you. C90 has wider support, C99 has some nifty features.

    There's also GNU C, which is what you get when you don't specify a standard to use. GNU C is standard C plus some GNU extensions. Confusing enough yet?

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    lol

    Actually, I was going to say that I worked my way around the problem by changing one of the options in the Quincy compiler

    It specified for strict ISO compliance, so I just unchecked that box, and everything works fine

    But yea, the information you provided was very helpful in my understanding though. I'll definitely keep the -std=c99 command in mind for possible need in the near future.

    Thanks a lot

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