multiple scnaf's problem !

[falcon eyez]

Hello every one

I faced a small problem while studying c++
I hope you can help me with it

my problem is
when I implement this code :

#include <stdio.h>
#include <math.h>
int main(void) {
	double h , x ,z;
	printf("Enter h  :");
	scanf("%lf",&h );
	printf("Enter x  : " );
	scanf("&lf",&x );
	z= x + h ;
	printf(" z=  " , z );
	return 0;
}

and I run the program
the program skips the second scanf :bored: ..
as a solution
I learned that I have to use fflush(stdin) between the two scanf's ..
..
ok , so what about this code .. ?

#include <stdio.h>
#include <math.h>
#define PI 3.14159
int main() {
	double side1, side2,side3,angle;
	printf("Enter side1 (cm): ");
	scanf("%lf",&side1);
	printf("Enter side2 (cm): ");
	scanf("%lf",&side2);
	printf("Enter angle in radians: ");
	scanf("%lf",&angle);
	side3 = sqrt(side1*side1+side2*side2-2*side1*side2*cos(angle));
	printf("side3 = %.2f cm\n",side3);
	return 0;
}

it's almost the same code as the first program .. but it never skips the second scanf !!

can anybody help me ..
..

to be clear ,my questions are :

1.where is the problem in the first program when the second program which is almost the same don't have any problem in it .. ?!

2.when and where should I use scanf and should I use fflush(stdin) between scanf's or not ?

best regards and thanks in advance

 

[falcon eyez]

Up :yell:​

.....

 

[falcon eyez]

Can someone help me with it please ?.. ?
my midterm is on Thursday ..