Thread: help with scanf...

I use printf & scanf in the program below.
I enter a value and then the value is used in the formulas.

But all the program does is printing

enter length :

and although I can put some number... the program does nothing.
No error, no warning, nothing...
It just stops there.

So I think there's something wrong aobut the scanf...
Can someone help me?

Code:

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

#define PI 3.14
#define g 9.807

int main(void)
{
    double period, length; 
        
    printf("enter length : ");
    scanf("%lf\n", &length);
        
    period=2*PI*sqrt(length/g);
    length=(period*period*g)/(4*PI*PI);
    
    printf("period is %g\n", period);
    printf("length is %g\n", length);        
    
    getch();
    return 0;
    }

I have executed your program.It worked correctly only.

I have received the following as a output of your program.

Output
--------
enter length : 2
period is 2.836
length is 2

For me it is asking two inputs because you have used newline in the scanf format.

If you removed that it will ask only one time.

Code:

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

#define PI 3.14
#define g 9.807

int main(void)
{
    double period, length;

    printf("enter length : ");
  scanf("%lf", &length);
    fflush(stdin);

    period=2*PI*sqrt(length/g);
    length=(period*period*g)/(4*PI*PI);

    printf("period is %g\n", period);
    printf("length is %g\n", length);

    return 0;
    }

Originally Posted by thillai_selvan

Can u tell me By which way have you compiled your code?
And can you ensure that you have compiled with -lm option?

I'm sorry I'm a newbie.
I don't understand your question.

I compile my program...well I use a compiler...I don't know which way the compiler does the compiling.

Originally Posted by sganesh

For me it is asking two inputs because you have used newline in the scanf format.

If you removed that it will ask only one time.

Code:

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

#define PI 3.14
#define g 9.807

int main(void)
{
    double period, length;

    printf("enter length : ");
  scanf("%lf", &length);
    fflush(stdin);

    period=2*PI*sqrt(length/g);
    length=(period*period*g)/(4*PI*PI);

    printf("period is %g\n", period);
    printf("length is %g\n", length);

    return 0;
    }

You're right!! I removed the \n and the program works! THANKS!