Hi all,
I'm trying to write a program that converts longitudinal and latitudinal co-ordinates from two places into x,y,z co-ordinates and calculates the surface distance between them. Part of the conversion calls for the addition of 90 degrees if the lattitudinal co-odinates are in the south or a subtraction if they are in the north. I was wondering how i would go about scanning in the North/ South portion of the input and comparing it with the formula so the program knows what to do next.


i appreciate any input at all

thanks,
Randall

what language?
How is the information inputted? Command line? File? Give an example of what the input would look like.

Sorry about the lack of information.

i'm doing this in C
and the input is a command line input

223(this would be the degrees), 30(this would be the minutes), 30(this would be seconds) North (the Direction)

so the input would be something like this
Please enter the lattitudinal and longitudinal co-ordinates:
223 30 30 North
145 45 15 West

essentially i will be scanning those numbers in and converting it into a final degree number and through a formula depending on whether it's North or South Lattitude you'll add or minus 90 degrees (this is where the problem is)
the same would apply for the East or west for the Longitude.

you mean...an IF statement?
/me all of a sudden feels stupid, since he's clearly missing the point

You'll have to parse the input somehow. I'd suggest looking at the strtok() function. You'd obviously want to use the space as your delimiter. As for the north/south/east/west bit. Look at the strcmp() function. Just be aware that strcmp is case-sensitive...

I've never used the strtok() function, so I can't really comment on how it works, but to do it down and dirty, I would suggest going through the whole input string and where ever there's a space, set it to 0 (null terminate). Then, using the address of the first character of each substring, use the atoi() function in <stdlib.h> to type cast the substring into an integer. For the Direction, it'll be a simple use of strcmp().

Here's a quick idea of what I mean, in case I didn't explain it well enough

------------------------------
#include<iostream.h>
#include<stdlib.h>


int main(){

char arr[] = {"123 456 678 test\0"};
short index = 0;
short x, y, z;


while(arr[index] != 0) // until string NULL terminated
{
if(arr[index] == 32) // if space
arr[index] = 0; // null terminate spaces

index++;
}

x = atoi(&arr[0]); // assign substrings
y = atoi(&arr[4]);
z = atoi(&arr[8]);

cout << x << endl;
cout << y << endl;
cout << z << endl;




return 0;
}

why not do this in perl? the perl parsing functions are a lot simpler and save a bit of code to do this

oooooh... well, maybe you shouldn't use strtok(). There's a suggestion not to use it in the man page. It's ok for simple stuff like this though.

sieranot's example would work just as well.

Here is an example that does not contain any error or range checking. It's better to use a character buffer, which you can tokenize and apply library functions to covert the input into integral types. That way you can validate the input.

The C++ fstreams are good for this, but most people are not familiar with them.

anyone ever use apstring.h? we have that in our class at school but have never seen anyone out in the "real world" ever use it.

You'll have to forgive me but i'm not too familiar with character arrays. i could barely follow some of the code sienarot wrote. i don't think i'll have too much trouble scanning in the numbers because i can deal with integers, it's the string comparison i am shaky on. i'm not at all familiar with the strcmp() function.

C is the first programming language i'm learning so i don't know much about Perl any any of those other languages.

Well, you can use the man pages for most functions.

man strcmp

will give you a description of the arguments it takes and what the return values are.

Is there anything particular that throws you off in its description?

Actually, you might want to use strcasecmp() instead; it is not a case-sensitive comparison.

I have an ideia that is simpler. So what you can do it ask for n, w, e and s, what includes all directions. And then do a swith with your options. Also, if you think it is easier you can treat a char as an integer (ASCII).

would i use it like this ?