Beginner question: passing values between functions

I'm trying to read in values with one function and then do a simple calculation and print the result using second function. In the end the program is going to be more complicated but that's what I started from.

However I ran into problems already. As the result I'm expecting ln(first input number) but that's not what I'm getting. I'm having doubts that the way I do it now wont pass values to second function but I'm not really sure either where the problem is.

That's the code I'm using:

Code:

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

double sisestus(double, double, double);
double arvutus(double, double);

main(void)
{
    double a,b,h;
    sisestus(a,b,h);
    
    double summa;
    arvutus(a, summa);
    
    printf("Vajuta suvalisele klahvile...");
    getch(); 
    return 0;
}


/*Sisestus*/
double sisestus(double s1, double s2, double s3)
{    
    printf("Sisesta argumendi vähim väärtus.\n");
    scanf("%lf",&s1);
    printf("Vähim väärtus on %3.2lf\n", s1);
    
    printf("Sisesta argumendi suurim väärtus.\n");
    scanf("%lf",&s2);
    printf("suurim väärtus on %3.2lf\n", s2);
    
    printf("Sisesta samm.\n");
    scanf("%lf",&s3);
    printf("Samm on %3.2lf\n", s3);	
}


/*Arvutamine*/
double arvutus(double s1, double s2)
{
    s2=log(s1);
    printf("%lf\n", s2);
}

Any help and explanation is appreciated.

Ok, you're not passing be reference. You need to send the address of your variables if you want your function to actually change their values (instead of just a copy of them).

You only pass the address of a value if you are using pointers

Code:

printf("%lf\n", s2);

scanf() uses %f for floats and %lf for doubles, while printf() uses %lf for floats and doubles.

getch() is typically in <conio.h>.

[edit]

Code:

printf("Vähim väärtus on %3.2lf\n", s1);

I think "&#228;" is an extended ASCII character; to use it in a program, you should probably figure out the ASCII value for it and convert it to octal, using it like this

Code:

"V\123him"

or convert it to hex and use it like this

Code:

"V\x1ahim"

You might want to look at these tutorials:

Lesson 4: Functions
Lesson 6: An introduction to pointers

[/edit]

Originally Posted by swgh

You only pass the address of a value if you are using pointers

Yes, which is typically what you'd want to do to alter an argument being passed to your function.

Originally Posted by dwks

while printf() uses %lf for floats and doubles.

No, printf() uses %f for floats and doubles.