Thread: Help creating function of sin cos and tan

i need to create a function that will convert an user input angle into all three sin cos and tan and display, i can do this without pointers and creating separate functions for each sin cos tan, but i want to know how to do this with pointers and in 1 function. Any websites or people to help? books ive used dont help much. ill explain more if necessary, thanks

Note: im new to C

How about you post some code showing what you have tried so far. What you need to know how to do this is in your textbook, if it's a book worth anything, that is. It may not have a specific example of what you want to do, but it will give you details on how to pass a pointer to a function, as well as calling functions from functions.

As for bundling everything up into one function, its maybe a matter of personal taste, but I prefer separating out different jobs into different functions. Make your function do one thing, and do that one thing well.

maybe i just need to understand pointers better but i just cant understand the point of pointers, they examples given are so simple there's no need for them, here's what i have done without pointers, and yes dwks thats exactly what i want to do. Also how would i do what i have currently done without using global variables, if i put them into the main i get errors, unless that is why pointers would be needed?

Code:

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


float angle, my_func1(void), my_func2(void), my_func3(void), my_func4(void);


main()

{

  
  printf("Enter Value in Degrees: ");
  scanf("%f", &angle);

  printf("Degrees: %f \n", angle);
  printf("Radians: %f \n", my_func1());
  printf("sin: %f \n", my_func2());
  printf("cos: %f \n", my_func3());
  printf("tan: %f \n", my_func4());

return(0);
}


float my_func1(void)
{
  
	return angle*M_PI/180;
}


float my_func2(void)
{
  return sin (angle) ;
}
 


float my_func3(void)
{
  return cos (angle) ;
}


float my_func4(void)
{

  return tan (angle) ;
}

Salem i don't understand what problem you are solving? but im guessing its, not using global variables, i tried it and the compiler says 'my_func' requires no argument, i take it its to do with the prototypes.

Howdy,

Just so happens, I'm working on getting a better understanding of pointers right now myself- so your question
inspired me to hack the following:

Code:

/*code to pass a pointer to a function which will calculate the */
/*sin, cos, and tan of an angle*/
#include<stdio.h>

#include<math.h>


void three_values(void *angle);

int main()
{  
	/*declare a variable to hold the angle value*/
	float ang;

	/*declare and initialize a pointer*/
	void *angle = &ang;

	printf("Enter the angle:\n");

	scanf("%f", &ang);

	three_values(angle);

	return 0;
}

void three_values(void *angle)
{
        int i;

	for(i = 1; i < 4; i++){

 	if(i == 1){
		printf("cos = %f\n", cos(*(float *)angle));}

	else if(i == 2){
		printf("sin = %f\n", sin(*(float *)angle));}

	else if(i == 3){
		printf("tan = %f\n", tan(*(float *)angle));}

	

	}
}

There are some interesting things you can do with void pointers, functions, and typecasting pointers.
The * dereferencing operator seems to be the key.

Hope this helps.

cq

ok no worries ive sorted it out, for future browsers heres the solution simple short and sweet.

Code:

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

void my_func(float ang,float* r, float* s, float* c, float* t)
{
    *r=ang*M_PI/180;
    *s=sin(*r);
    *c=cos(*r);
    *t=tan(*r);
}

main()

{
  float angle,radians,sinang,cosang,tanang;
  printf("Enter Value in Degrees: ");
  scanf("%f", &angle);
  my_func(angle,&radians,&sinang,&cosang,&tanang);
  printf("\nDegrees: %f \n", angle);
  printf("Radians: %f \n", radians);
  printf("Sin: %f \n", sinang);
  printf("Cos: %f \n", cosang);
  printf("Tan: %f \n", tanang);

return(0);
}

Howdy Quzah,

Yep, I see your *point. A void pointer is useless overkill.

The whole thing was an exercise of my own to use void pointers, void functions, and typecasting.

Thanks again for your critique.

cq