How Can I Fix My C While Loop Issue in Calculating Factorials?

[Vavotaj]

#include <stdio.h>
#include <string.h>

double faktoriel (double y);

void main()
{
double x, fac;
char yes[5] ="yes";
char answer[5];

do
{
printf("Enter number:\n");
scanf("%f", &x);

while (50>x || x>100)
{
printf("Number doesn't match \n"); //50<x<100
printf("Enter number again:\n");
scanf("%f", &x);
}
fac = faktoriel (x);
}while(strcmp (yes, answer)!=0);
return;
}

double faktoriel (double y)
{
double i, factor;


for(i=y; i>1; i--)
{
factor*=i;
}
printf("%f", factor);
return factor;
}
----------------------------------------------------------------------------------------
There are proly many mistakes xD

 

[Borek]

while (50>x || x>100)

//50<x<100

No idea what you are trying to do, but this is inconsistent.

 

[Vavotaj]

to ppl enter number lower than 100 higher than 50

 

[Borek]

x>100 doesn't mean lower than 100.

 

[Vavotaj]

but while x is higher than 100 or lower than 50 to to that code

 

[Vavotaj]

or how should it be done ?

 

[KTC]

x > 100

means precisely what it suggest, x is greater than 100.

And || is OR, I think you were wanting && (AND).

 

[chroot]

The line of code that Borek pointed out is, in fact, correct. It will keep asking the user to enter a value until it's between 50 and 100.

Your post contains no questions, though, so I have no idea what you want from us.

- Warren

 

[Borek]

The line of code that Borek pointed out is, in fact, correct.

Oops, sorry. I was absolutely sure it was x>50 || x>100. Must be senior moment

 

[Vavotaj]

than why it is always repeating it self even if i enter number between 50 and 100 ?

 

[Vavotaj]

for exaple :
#include <stdio.h>

main()
{
double x;

printf("Enter number:");
scanf("%f", &x);

while (50>x || x>100)
{
printf("Number doesn't match \n");
printf("Enter number again:\n");
scanf("%f", &x);
}
}

 

[Vavotaj]

it works with int ... why it doesn't work with double ?

 

[D H]

It is always a good idea to run a program with a debugger. If you do this you will find that the value of x is nowhere close to the value you typed in. Hint: Your example program will work if you change x from a double to a float.

 

[Vavotaj]

but how do i do it in double ?

 

[computerex]

You write programs to solve problems. Based on the complexity of your problem, you devise a solution that is most efficient/productive. What is your problem?

 

[Vavotaj]

my professor ... he demands double

 

[Vavotaj]

ah solution :
#include <stdio.h>

main()
{
float x;


(double) x;
printf("Enter number:");
scanf("%f", &x);
while (50>=x || x>=100)
{
printf("Number doesn't match \n");
printf("Enter number again:\n");
scanf("%f", &x);
}
}
:)

 

[D H]

but how do i do it in double ?

I could tell you right now how to solve this problem, but that will not help you solve related problems in the future. You need to learn how to use reference material. There is no way to keep all the stuff associated with a language and its associated libraries in your head. The ability to quickly look things up in the reference material is key to having any success in programming.


So, I will instead tell you to RTFM: Read The Fine (or if you prefer, some other F word that is a tad more vulgar) Manual. I'll even give a specific thing to read up on this time: scanf. If you are still vexed, ask again, but please only do so after you have read the documentation.

 

[D H]

my professor ... he demands double

ah solution :
float x;


(double) x;

You will (or at least should) get points off if you offer this as your solution. In particular, (double) x; does absolutely nothing useful. In particular, it is not doing what your professor has asked of you.

 

[Vavotaj]

All i have bout scanf is int, char and float ... double is not mentioned

 

[Borek]

10 seconds googling.

http://www.rt.com/man/scanf.3.html

 

[Vavotaj]

Solution :

#include <stdio.h>

main()
{
double x;
printf("Enter number:");
scanf("%lf", &x);
while (50>=x || x>=100)
{
printf("Number doesn't match \n");
printf("Enter number again:\n");
scanf("%lf", &x);
}
}

 

[Vavotaj]

Solution :

#include <stdio.h>

main()
{
double x;



printf("Enter number:");
scanf("%lf", &x);
while (50>=x || x>=100)
{
printf("Number doesn't match \n");
printf("Enter number again:\n");
scanf("%lf", &x);
}
}

 

[D H]

Excellent. RTFM is a powerful technique. Except when the Fine Manual is not so fine, that is.

 

[Vavotaj]

Actualy Lousy Manual didn't have it so i looked at google more precise xD

 

[KTC]

Solution :

#include <stdio.h>

main()
{
	double x;
	

	
	printf("Enter number:");
	scanf("%lf", &x);
	while (50>=x || x>=100)
	{
		printf("Number doesn't match \n");
		printf("Enter number again:\n");
		scanf("%lf", &x);
	}
}

You're either coding to C90, in which case you can drop the "int" in front of main(void), but you'll have to explicitly specify a return value; or C99, in which case you have to have the "int" in front of main(void), but can let the return value be implicit; or C++, where you don't need the void, but otherwise the same as C99.

 

[chota]

return type double :/
I am not sure what your prof wants you to write code about, Instead of just directly pasting code, can you also post what it is you are trying to code. MOre help can be granted to you that way