在C中调用一个没有输出变量的函数

Question

This is how it looks now but it's telling me that the variable 'result' is unused. Why is this? I think I've figured out the use of the function in this program but I can't configure everything quite yet. Still need some help, thanks.

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

double computeSomething(unsigned int maxDamage, unsigned int minDamage,
                        double playerArmor, double actualDamage);

int main(void){

    double playerHealth, playerArmor, actualDamage, result = 0;
    unsigned int minDamage, maxDamage;

    printf("Enter Player Health:     ");
    scanf("%lf", &playerHealth);
    printf("Enter Player Armor (0.0 - 1.0):   ");
    scanf("%lf", &playerArmor);
    printf("Enter Minimum Damage Dealt:  ");
    scanf("%u", &minDamage);
    printf("Enter Maximum Damage Dealt:   ");
    scanf("%u", &maxDamage);

    srand((unsigned int) time(NULL));

    while (playerHealth > 0) {

        double result = computeSomething(maxDamage, minDamage, playerArmor,     actualDamage);
        playerHealth -= actualDamage;

        printf("Current Player Health:%.2lf\tDamage Dealt: %.2lf\t",      playerHealth, actualDamage);
        if (playerHealth > 0){
            printf("Alive: 1\n");
        } else {
            printf("Alive: 0\n");
        }
    }

    return 1;
}

double computeSomething(unsigned int maxDamage, unsigned int minDamage,
                        double playerArmor, double actualDamage)
{
     actualDamage = ((rand() % (maxDamage-minDamage + 1)) + minDamage) * (1 -     playerArmor);

    return actualDamage;
}

Answer 1

Edit 3

Change your prototype from:

double computeSomething(unsigned int maxDamage, unsigned int minDamage,
                        double playerArmor, double actualDamage);

To:

double computeSomething(unsigned int maxDamage, unsigned int minDamage,
                        double playerArmor, double *actualDamage);  

Call it like this:

float res;
computeSomething(34, 15, 30.5, &res);  

See my latest example below for how to modify the result in the actual function.

I can't create a function to call for. That's literally all I need to do.

This defines a function that is called from main() ;
(For something more specific, describe it specifically)

EDIT

Added a function that is passed values, computes something, and returns results. Perhaps you can apply the principles here to your problem. (I do not fully understand your needs from the description you have provided)

//prototypes
void PrintSomething(char *str);
float compute_something(float x, float y, float z);//per clarification in comments above  
void return_through_param(float x, float y, float *result);
int main(void)
{
    PrintSomething("Hello World\n");
    //function that can return something
    float result = compute_something(10.0, 3.5, .002);
    printf("Here are the results: %f\n", result); 

    //for Edit 2:
    return_through_param(10, .0001, &result);
    printf("This is the new result: %f\n", result);

    return 0;
}  

void PrintSomething(char *str)
{
     printf(str);
}
//Edit - Added this function
float compute_something(float x, float y, float z)
{
    return x*y/z;
}  

//Edit 2 - added this function that passes pointer, for output
void return_through_param(float x, float y, float *result)
{
     return *result = x/y;
}