kind of new here and need help

**yasharm** · 01-02-2007

i know it may is very simple but can someone tell me how to ask a question in c
Ive tried everything i could but i cant figure this out when i ask do you want to enter a new value if ans is y do this otherwise do nothing can someone please help

Code:

#include<stdio.h>
#include<math.h>

float R1;
float R2;

float Rf;
float Rf2;

float Vin;
float Vin2;

float Vout;
float Vout2;

int ans;
int n;
int y;

void main(	)
{
		
do
{
printf("Please  enter  a value  for Voltage -->");
scanf("%f",&Vin); 
}while(Vin<0);
	
	do
	{
	printf("Please enter a value for Resistor 1 -->");
	scanf("%f",&R1);
	}while(R1<0);

		do
		{
		printf("Please enter a value for Resistor f -->");
		scanf("%f",&Rf);
		}while(Rf<0);

			
		Vout=-Rf*(Vin/R1);
		printf("Voltage  out  is =%f \n\n",Vout);
		printf("Your Voltage in was%f \n\n",Vin);

		
	printf("Would you like to enter a new value?(y/n)\n\n");
	scanf("%d",n,y);
				
if(ans=y)
	{
	
	do
	{
	printf("Please  enter  a value  for Voltage -->");
	scanf("%f",&Vin2); 
	}while(Vin2<0);
			
		{
		printf("Please enter a value for Resistor 1 -->");
		scanf("%f",&R2);
		}while(R2<0);
		
	               {
		printf("Please enter a value for Resistor f -->");
		scanf("%f",&Rf2);
		}while(Rf2<0);
			
		Vout2=-Rf2*(Vin2/R2);
		printf("Voltage  out  is =%f \n\n",Vout2);
		printf("Your Voltage in was%f \n\n",Vin2);
		
}
else
{	
scanf("%d",n);
printf("Thank you for using the program please press enter to terminate the program\n\n\n\n",n);
									
}

}

**quzah** · 01-02-2007

main is not a void function, ever. There's a FAQ on it. It returns an int.
= is for assignment.
== is for testing equality.
scanf expects all of its arguments to be pointers.

Thus, if you are trying to pass it a non-pointer, you'll need to pass its address. Like so:

Code:

scanf( "%c", &answer );
if( answer == 'y' || answer == 'Y' )
{
    ...do stuff...
}

Something like that. Your indenting could use a bit of work. Try replacing spaces with tabs, and just indenting four spaces every after { lines and unindenting after }.

Quzah.

**vart** · 01-02-2007

Don't use globaal vars
Don't pass to scanf wrong number of params:

Code:

scanf("%d",n,y);

This is wrong.
Always pass exactly the same number of argument as you want to read with the format.

Instead of repeating your code twice - use function or loop

**yasharm** · 01-03-2007

i did what you mentioned but it just go to where i said (ans=n)

Code:

			printf("Would you like to enter a new value?(y/n)\n\n");
			scanf("%c",&ans);
				
if(ans == 'y' || ans == 'Y')
	{
	
	do
	{
	printf("Please  enter  a value  for Voltage -->");
	scanf("%f",&Vin2); 
	}while(Vin2<0);
			
		{
		printf("Please enter a value for Resistor 1 -->");
		scanf("%f",&R2);
		}while(R2<0);
		
			{
			printf("Please enter a value for Resistor f -->");
			scanf("%f",&Rf2);
			}while(Rf2<0);
			
				Vout2=-Rf2*(Vin2/R2);
				printf("Voltage  out  is =%f \n\n",Vout2);
				printf("Your Voltage in was%f \n\n",Vin2);
		
}
		else
		{	
		printf("Thank you for using the program please press enter to terminate the program\n\n\n\n",n);
		scanf("%c",&ans);						
			
		}

**vart** · 01-03-2007

Remove ,n from the printf - your supplied arguments fro printf should be complient with the format

Code:

printf("Thank you for using the program please press enter to terminate the program\n\n\n\n",n);

This code works:

Code:

#include <stdio.h>
int main()
{
	char ans;
	printf("Would you like to enter a new value?(y/n)\n\n");
	scanf("%c",&ans);
				
	if(ans == 'y' || ans == 'Y')
	{
	}
	
	else
	{	
		printf("Thank you for using the program please press enter to terminate the program\n\n\n\n");
		scanf("%c",&ans);						
		
	}
}

But note that the scanf leaves the '\n' symbol in the input buffer
so if you try to read one more char it will read this symbol instead of the new answer.

So you should flush the input buffer before asking a new question
You read the FAQ to find out the way to do it : http://faq.cprogramming.com/cgi-bin/...&id=1043284392

**yasharm** · 01-03-2007

its working on its own but when i put it in the program it does the same thing

**vart** · 01-03-2007

have you implemented also the flushing like it is described in the FAQ?

**yasharm** · 01-03-2007

Thankx Vart and quzah you guys been very helpfull programs workiong thanx a lot

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