Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

Converting from a string to char

Posted on 2004-04-27
15
Medium Priority
?
392 Views
Last Modified: 2010-04-02
Basically im trying to make a small calculator...

arguments would be as follows on the command line

calculator.out 3 + 6
3 arguments are passed

i have no problem with the 3 or 6

i need to convert the second arguement from a string of length 1 to a char and assign it to a variable.

Urgently needed

Thanx
0
Comment
Question by:Pol_88
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 4
  • 2
  • +2
15 Comments
 
LVL 1

Expert Comment

by:hal3000
ID: 10934509
Hi Pol_88,

A string is an array of chars. The first element of the array is the first char in the string.

If you are having trouble with the "+", I wonder if you are having trouble with the "3" and the "6" strings being passed.

Good luck
0
 
LVL 11

Expert Comment

by:avizit
ID: 10934512
use the c_str() function

but beware it has some pitfalls

so when you use it ..store it in another variable using strdup()

additionally read up  http://www.bcbdev.com/articles/suggest.htm#cstr

/abhijit/

0
 
LVL 11

Expert Comment

by:avizit
ID: 10934516
oops wrong answer .. please ignore
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 11

Expert Comment

by:avizit
ID: 10934564
Maybe this is what you wanted

#include <stdio.h>

int main(int argc, char **argv){
        int a = atoi(argv[1]);
        int b = atoi(argv[3]);

        printf("a is: %i\n",a);
        printf("b is: %i\n",b);
        printf("c is: %c\n",argv[2][0]);
        return 0;
}

if i run it like a.out 3 + 6  i get the following output

$ ./a.exe  3 + 6
a is: 3
b is: 6
c is: +

so if you just want the first character of the second srtring just use argv[2][0]

/abhijit/
0
 

Author Comment

by:Pol_88
ID: 10934568
Im not having problems with the 3 and the 6

i brought them in with int main (argc, char* argv[])
only the +

i tried this so far..

int main (argc, char* argv[])
double one, three;
char operator[1];

one = atof(argv[1]);
three = atof(argv[3]);
operator = argv[2];
0
 

Author Comment

by:Pol_88
ID: 10934585
Why wont it let me do  operator = argv[2];  ??
0
 
LVL 11

Expert Comment

by:avizit
ID: 10934632
you can do

operator = argv[2][0]  to get the first character of the character array argv[2]

/abhijit/
0
 

Author Comment

by:Pol_88
ID: 10934644
Is there anyway of doing this without multidimensional arrays?
0
 

Author Comment

by:Pol_88
ID: 10934953
thanx for trying to help...

i figured it out
....

int main (int argc, char* argv[])
{
char operator;
double one, three, tot;

one = atof(argv[1]);
three=atof(argv[3]);
operator=*argv[2]);

if (operator=='+')
....................
0
 
LVL 10

Accepted Solution

by:
Mercantilum earned 252 total points
ID: 10934964
Your aguments come as an array of pointers to strings. A string being an array of chars...
argv[0] -> "3"
argv[1] -> "+"
argv[2] -> "6"
"3" being an array of 2 chars: { '3', 0 }

So, using arguments you have not much choice.
(by the way, beware that with some operators like '*' you may have some troubles as
  prog.out  3 * 6
will expand * with the list of files in your directory :)

What I would do here is forget the arguments passing and ask user to input it, e.g.

#include <stdio.h>
main()
{
   double a,b;
   char op;

   printf ("Please enter x OP y : ");
   scanf ("%lf %c %lf", &a, &op, &b);
   // check what we got
   printf ("This is what I got: %lf %c %lf\n", a, op, b);
}
0
 
LVL 9

Expert Comment

by:ankuratvb
ID: 10937773
Using arguments,you'd also have problems if the user types 3*6 without spaces,then all of it will be stored in argv[1].

Use mercantilum's suggestion with scanf,it gets pretty easy that way.
0
 
LVL 9

Assisted Solution

by:ankuratvb
ankuratvb earned 248 total points
ID: 10938649
Using Mercantilum's code,you get the operands directly as double which you can operate on(no atoi required).and you have the operator in a single char.
You could do a switch on the operator and evaluate accordingly:

switch(op)
{
 case '+':res=a+b;break;
 case '/':res=a/b;break;
 default:printf("Invalid Operator");break;
}
0

Featured Post

VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

Question has a verified solution.

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

Have you thought about creating an iPhone application (app), but didn't even know where to get started? Here's how: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Important pre-programming comments: I’ve never tri…
Preface I don't like visual development tools that are supposed to write a program for me. Even if it is Xcode and I can use Interface Builder. Yes, it is a perfect tool and has helped me a lot, mainly, in the beginning, when my programs were small…
The goal of this video is to provide viewers with basic examples to understand how to use strings and some functions related to them in the C programming language.
The goal of this video is to provide viewers with basic examples to understand opening and reading files in the C programming language.

609 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