Thread: please help quick, brainfart moment should be easy solution

  1. 12-05-2010 #1
    fourseventwo
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    please help quick, brainfart moment should be easy solution

    Ok, this is kinda embarassing but im having trouble with the beginning of my code. i need help quickly to get this project done. The code is supposed to display the options below, (1-5) and then scan for user input. instead my program is just endless loooping without scanning. any help? i think a new persepctive is all i need.
    ive posted the problem bit below.


    Code:
    int main () {
	flowratetable.name==NULL;
	userinterface();
}


void userinterface(){
	int quit=0, exit=0;
	int option=0;
	while (quit==0){
	printf("\t1. Create a flow rate table\n\t2. Load an existing flow rate table\n\t3. Display currenty loaded flow rate table\n\t4. Estimate water depth using flow rate table\n\t5. Terminate\n\n");
	if (flowratetable.name != NULL ){
		printf("Table %s Loaded", flowratetable.name);
	}
	else if (flowratetable.name == NULL){
		printf("No Table Loaded");
		while (exit=0){
			scanf("%i\n", &option);
			if (option==1){
				addflowratetable();}
			if (option==2){
			loadflowratetable();}
			if (option==3){
			displayflowratetable();}
			if (option==4){
			estimatewaterdepth();}
			if (option==5){
				printf("Terminating\n");
			quit=1;}
		}
	}}}
  2. 12-05-2010 #2
    claudiu
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    while(exit=0)

    you really need to start compiling with ALL WARNINGS on.
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.
  3. 12-05-2010 #3
    fourseventwo
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    i fixed that but it still keeps infinite looping...
  4. 12-05-2010 #4
    claudiu
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    Well of course it is going to be looping since exit will always be 0. You never change it. That's another warning you should have gotten.
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.
  5. 12-05-2010 #5
    tenchu
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    I also recommend changing the variable name. It's alright to name it exit, but exit is also the name of a function exit(0); in one of the standard libraries. It could get confusing, so better to practice not using exit as a name.

    The other posters have posted helpful tips!

    I would like to offer an idea. Instead of looping in a weird while loop, I think looping within in infinite for loop is better, and put in a case that can break the loop. (you still need to define when exit isn't 0 though, as one of the users pointed out)

    Code:
    for (;;){
 // some code

 printf("Do you want to exit this weird loop? Enter something...Yes = >0, No = 0.");
 scanf("%d", &exit);
 if (exit != 0)
   break;
}
    Of course you don't need to ask the user, you can set it up so the program knows when to switch exit to something >0. You could also use character Y or y, or N or n, and loop while the user doesn't press N or n when asked if they want to exit. Makes more sense than simply looping while something is 0.

    You need to be careful with break because sometimes it can set you back to a place where you may not want to be. It is good fun to use though! You can also use more advanced stuff like setjmp and longjmp but I think those are unneeded in most cases and probably frowned upon, along with goto statements.
    Last edited by tenchu; 12-05-2010 at 09:57 PM.
  6. 12-05-2010 #6
    renzokuken01
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    not because when you WERE a beginner and wrote codes (loops) this way, doesn't mean those you condescend do write them like this. i've seen dozens of functions with more than 1600 lines of codes, without any comments, mostly in giant loops, that you practically have to keep the whole function in your head, to see it from the large scale until the smallest, most core details. and this is just in one side of the project....

    i know this is against my code to reveal insights, but there are people out there that will only speak of trivial things, as they are careful not to reveal trade secrets.

    it's funny how "nerdy" people just get to programming as a "side-dish", and see how it works and thinks whatever works is just as good as any solutions. yet put them in a real computational complexity lecture hall and watch their dumbfounded faces as they see why how they've been doing things are very inefficient.
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