Newton’s Second Law of Motion: force = mass * acceleration

[brianjoo]

Write your question here.
I'm new to c++, but have some experience with coding.
I'm not sure why my program is not doing what i want it to do.
I want the user to input two values(doubles) to be the mass and acceleration, and then I want the values to be multiplied by each other.

  #include <stdio.h>

int main(void) {
	double mass=0.00, acceleeration=0.00 , force=0.00 ;

	//1. Promot the user for the mass and acceleration
	printf("Please enter the mass and accleeration <both floating-points values> for use in Newton's Second Law ");

	//2. Get the mass and accleration from the user
	scanf("%f %f", &mass, &acceleeration);

	//printf("%d %d\n", mass, acceleeration);


	//3. Mutliply the mass with accelleration
	force = mass * acceleeration;

	//4. Put it together
	printf("Newton's Second Law: force = mass*acceleeration= %f\n",force);




}

Thanks a ton for helping.

[Ganado]

C's scanf will not work correctly if it's looking for the wrong data format.

When I compile your code, I get the warning format '%f' expects the argument of type 'float*' but argument 2 (and 3) has type 'double*' [-Wformat=]

The format specifier %lf (long float) is used for doubles, not %f.
C's library is picky about that stuff, and makes the end-user do the formatting work.

EDIT: You also want to put fflush( stdout ); right after your printf statement, or else the user may not see the initial prompt.

_______________________

Side note: Since you seem to want to learn C++ and not C, I would suggest using the <iostream> library with a modern compiler

#include <iostream>
int main()
{
    double mass = 0.0;
    double acceleration = 0.0;
    double force = 0.0;

    std::cout << "Please enter the mass and accleeration <both floating-points values> for use in Newton's Second Law " << std::endl;
    std::cin >> mass >> acceleration;

    force = mass * acceleration;
    std::cout << "Force = " << force << std::endl;
}

[keskiverto]

What is the observed problem?

Could these remarks relate to the issue?

10:38: warning: format '%f' expects argument of type 'float*', but argument 2 has type 'double*' [-Wformat=]
10:38: warning: format '%f' expects argument of type 'float*', but argument 3 has type 'double*' [-Wformat=]

PS. The line 12, if uncommented, produces:

12:39: warning: format '%d' expects argument of type 'int', but argument 2 has type 'double' [-Wformat=]
12:39: warning: format '%d' expects argument of type 'int', but argument 3 has type 'double' [-Wformat=]

PS2. You say "new to c++", and then show code written in C. (It is valid C++, but C++ has other, more convenient I/O options).

[brianjoo]

oh i thought it was c++. im taking a course, and my intructor told us to do it like that.