# Thread: Equivalent Resistance of ciircuit

1. ## Equivalent Resistance of ciircuit

What is wrong with this code?

Code:
```#include <stdio.h>

int R_series(int r[100]);
int R_par(int r[100]);

int main (){

//Jeremy Zarabi
//ESE 124 HW 12

int num1, start=1;

while (start==1){
printf("Enter 0 to quite\n Enter 1 for series circuit\n Enter 2 for parallel circuit: ");
scanf("%d",&start);

if (start==0){
return 0;
}

else if (start==1){
R_series=R_series(r);
printf("Equivalent Resistance of your circuit=%d Ohms\n",R_series);

printf("Enter 0 to quite\n Enter 1 for series circuit\n Enter 2 for parallel circuit: ");
scanf("%d",&start);
}

else if (start==2){
R_par=R_par(r);
printf("Equivalent Resistance of your circuit=%d Ohms\n",R_par);

printf("Enter 0 to quite\n Enter 1 for series circuit\n Enter 2 for parallel circuit: ");
scanf("%d",&start);
}

else if (start==0||start==1||start==2)
printf("Error!")

}
}

int R_series (int r[100]){
int num1;
printf("How many resistors are connected in series: ");
scanf("%d",&num1);

printf("Enter value of each resistance: \n");
for (int i=0;i<num1;i++)
{
printf("\nR_%d: ", i+1);
scanf("%d",&r[i]);
}
for (int j=0;j<num1;j++)
R_series+=r[j];
}

int R_par(int r[100]){
int num2;

printf("How many resistors are connected in parallel: ");
scanf("%d",&num2);

printf("Enter value of each resistance: \n");
for (int i=0;i<num1;i++)
{
printf("\nR_%d: ", i+1);
scanf("%d",&r[i]);
}
for (int k=0; k<num2;k++){
R_par+=(1.0/r[i]);
}
R_par=1.0/R_par;
}```

2. You keep using the variables R_series and R_par but I don't see them declared anywhere.

3. Originally Posted by tabstop
You keep using the variables R_series and R_par but I don't see them declared anywhere.
I think they are functions; but, where is the "r" array of 100 ints defined?

Tim S.

4. the r array is scanned in the two call functions and has a max memory of 100 elements

5. Originally Posted by jjzarabi
the r array is scanned in the two call functions and has a max memory of 100 elements
Yes, but you have to pass a real, actually-existing array into the function. Which you don't. You also can't try to use the name of a function inside the function as a variable, because after all this isn't Fortran. (All your variables need to be declared, when it comes down to it. Start declaring some variables.)