Solved

Doing calculations with arrays - invalid operands to binary

Posted on 2008-06-10
4
643 Views
Last Modified: 2010-04-21
Hi,
I'm new to C programming but feel i'm pretty good at perl so I feel like I really should be able to do this.
I've looked at C tutorials and in several text books but I can't find anything which helps.

All I want to do is do some calculations with arrays of data.
for (i=1; i<=d; i++)
a[i] = b[i] / c[i];
Why does this give me the error message: invalid operands to binary /. I'm using Dev-C++.
The division seems to be causing a problem.
I've tried all data types. I want to use double or float.
I'm adding to an existing C program and earlier in the program there is this code:
for (i=1; i<=x; i++)
y[i] = z[i]  /  t;
This works but mine doesn't.

This type of thing is easy in perl but i've spent ages on this.

Can anyone tell me how to work through arrays and perform calculations on each element or point me to a useful website. Thanks


0
Comment
Question by:csnell
4 Comments
 
LVL 45

Accepted Solution

by:
sunnycoder earned 50 total points
ID: 21749650
Hello csnell,

What you have written is fine and should work ... can you post complete code ...

Or you can try this small example.

#include <stdio.h>

int main ()
{
    float a[] = { 1.1, 2.2, 3.3 };
    float b[] = { .1, .2, .3 };
    float c[3];
    int i;

    for (i=0; i<3; i++)
        c[i] = a[i]/b[i];
    for (i=0; i<3; i++)
        printf ("%f\t",c[i]);
}

Regards,
sunnycoder
0
 
LVL 53

Expert Comment

by:Infinity08
ID: 21749651
First, array indexing in C starts at 0, not 1, so most likely :

        for (i=1; i<=d; i++)

has to be :

        for (i=0; i<d; i++)

where d is the length of the array.

About the division not working : can you show how you defined the arrays a, b and c ?
0
 
LVL 40

Expert Comment

by:evilrix
ID: 21749665
It should be more or less the same as Perl... try this...
#include <iostream>
 
int main()
{
	int a[] = {1,2,3,4,5};
	int b[] = {1,2,3,4,5};
 
	for(size_t i = 0 ; i < 5 ; ++i)
	{
		std::cout << a[i] << "/" << b[i] << "=" << a[i]/b[i] << std::endl;
		std::cout << a[i] << "*" << b[i] << "=" << a[i]*b[i] << std::endl;
		std::cout << a[i] << "+" << b[i] << "=" << a[i]+b[i] << std::endl;
		std::cout << a[i] << "-" << b[i] << "=" << a[i]-b[i] << std::endl;
	}
}

Open in new window

0
 

Author Closing Comment

by:csnell
ID: 31465662
Thanks for your help.
It wasn't working because when I had initialized the arrays I had used *. I had looked at what had been done previously in the program for what I thought were arrays. I now know they are pointers!. I have only just begun to understand the basics of pointers so I didn't notice my error.
0

Featured Post

Three Reasons Why Backup is Strategic

Backup is strategic to your business because your data is strategic to your business. Without backup, your business will fail. This white paper explains why it is vital for you to design and immediately execute a backup strategy to protect 100 percent of your data.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
count11 challenge 6 70
base64 decode encode 12 133
Unable to start eclipse ? 17 141
gdb doesn't stop on breakpoint 2 67
An Outlet in Cocoa is a persistent reference to a GUI control; it connects a property (a variable) to a control.  For example, it is common to create an Outlet for the text field GUI control and change the text that appears in this field via that Ou…
This article is meant to give a basic understanding of how to use R Sweave as a way to merge LaTeX and R code seamlessly into one presentable document.
The viewer will learn how to use the return statement in functions in C++. The video will also teach the user how to pass data to a function and have the function return data back for further processing.
The viewer will learn additional member functions of the vector class. Specifically, the capacity and swap member functions will be introduced.

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question