Store as separate variables C programming

Question

Hi Im trying to store two get_input methods as separate variables but I am not sure how. Also my get_input in the main method keeps saying its implicitly differentiated please help

#include <stdio.h>

double main()
{
   get_input();
   get_input();
}

double get_input(void)
{
   double x1;
   printf("Enter any number: ");
   scanf("%lf", &x1);
   return x1;
}

double get_next(double x2,double x1)
{
   double total;
   total=(((x2)/2)+3(x1));
   return total;
}

void print_result()
{
   return null;
}

Answer 1

Your compiler is complaining that it doesn't know about your function get_input. Compiling is done top-to-bottom, so when it reaches:

double main()
{
    get_input();

Your compiler doesn't know what get_input is. You need to declare (optionally define) your function before main.

double get_input();
double main()
{
    get_input();

This is called a function prototype and even though get_input hasn't been defined, the compiler at least knows it exists and can continue compiling.

You probably want to assign the return of get_input to a value for later use:

double value = get_input();

Answer 2

If you are new to C/C++, few basic things and you can rewrite your program as shown below.

#include <stdio.h>

//Function declarations
double get_input(void);
double get_next(double x2,double x1);
void print_result();

int main( int argc, char *argv[])
{
   double d1, d2;
   d1 = get_input();
   d2 = get_input();
   return 0;
}

double get_input(void)
{
   double x1;
   printf("Enter any number: ");
   scanf("%lf", &x1);
   return x1;
}

double get_next(double x2,double x1)
{
   double total;
   total=(((x2)/2)+3(x1));
   return total;
}

void print_result()
{
   return;
}

Answer 3

any chance that actually said implicitly defined? If so I suspect that the problem is that you are calling your functions before defining them. To fix this you have 2 options:

1.reorder - for this solution, you will want to make sure that no functions are used before being created. In your case the problem would be using get_input() in main.

#include <stdio.h>

double get_input(void)
{
    double x1;
    printf("Enter any number: ");
    scanf("%lf", &x1);
    return x1;
}
double get_next(double x2,double x1)
{
    double total;
    total=(((x2)/2)+3(x1));
    return total;
}
void print_result(void)
{
    return null;
}
double main(void)//move main to the bottom
{
    get_input();
    get_input();
}

2.prototypes

#include <stdio.h>
double_getinput(void);
double get_next(double x2, double x1);//double get_next(double, double); also works, I just think this looks better
void print_result();

double main(void)
{
    get_input();
    get_input();
}
double get_input(void)
{
    double x1;
    printf("Enter any number: ");
    scanf("%lf", &x1);
    return x1;
}
double get_next(double x2,double x1)
{
    double total;
    total=(((x2)/2)+3(x1));
    return total;
}
void print_result(void)
{
    return null;
}

Also, main should always look like one of the following:

1

!implicit void param~ (Apparently invalid)

int main(){//
    ...
    return 0;
}

explicit void param (a little less common, but I would recommend this for you)

int main(void){
    ...
    return 0;
}

explicit command line args (second most common)

int main(int argc, char *argv){
    ...
    return 0;
}

NOTE: the int is also optional for all of these forms. For example (I HIGHLY discourage this option):

main(void){
    ...
    return 0;
}

EDIT the reason main should be formatted like this Regarding 'main(int argc, char *argv[])'