Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

help converting integers to strings and concatenating in C

Posted on 2012-03-16
11
Medium Priority
?
365 Views
Last Modified: 2012-03-16
I'm trying to convert two integers into strings, concatenate them, and convert the result back to an integer. I'm not sure the best way to do this. I tried using sprintf but it didn't work and the characters were null when I printed them out.

Here are the relevant parts of the code:

alt_u8 high_digit, low_digit;
char high_digit_char, low_digit_char, full_value_char;

sprintf(high_digit_char, "%d", high_digit);
sprintf(low_digit_char, "%d", low_digit);
sprintf(full_value_char, "%s %s",high_digit_char, low_digit_char);
      
full_value = atoi(full_value_char);
0
Comment
Question by:frostyourself
[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
  • 7
  • 4
11 Comments
 
LVL 84

Expert Comment

by:ozo
ID: 37731487
char high_digit_char[2], low_digit_char[2], full_value_char[3];
sprintf(high_digit_char, "%d", high_digit%10);
sprintf(low_digit_char, "%d", low_digit%10);
sprintf(full_value_char, "%1s%1s",high_digit_char, low_digit_char);
full_value = atoi(full_value_char);
0
 
LVL 84

Expert Comment

by:ozo
ID: 37731495
//or
 char full_value_char[99];
 sprintf(full_value_char, "%d%d",high_digit,low_digit);
0
 
LVL 84

Expert Comment

by:ozo
ID: 37731504
if you use full_value_char[3],
"%1s%1s" should have been "%.1s%.1s"
0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 

Author Comment

by:frostyourself
ID: 37731565
I'm still not getting the correct result, these are the integer and corresponding character values printed out:

high int: 18 low int: 18
full val int: 2c
low char: 4 high char: 4
full char: 44

What is the point of the %10 in high_digit%10 within the sprintf?

Maybe I should post another part of the code:

high_digit = bcd_convert(high_digit);
low_digit = bcd_convert(low_digit);

alt_u8 bcd_convert(alt_u8 val_convert)
{
      switch(val_convert){

            case 0:
                  val_convert = 0xC0;
                          break;
            case 1:
                  val_convert = 0xF9;
                      break;
            case 2:
                  val_convert = 0x24;
                      break;
            case 3:
                  val_convert = 0x30;
                      break;
            case 4:
                  val_convert = 0x19;
                      break;
            case 5:
                  val_convert = 0x12;
                      break;
            case 6:
                  val_convert = 0x03;
                      break;
            case 7:
                  val_convert = 0xF8;
                      break;
            case 8:
                  val_convert = 0x00;
                      break;
            case 9:
                  val_convert = 0x18;
                            break;
                                             }
      return val_convert;
}

The high digit and low digit are converted to these hex values, so for example if high digit is 9 and low digit is 9, I would want "1818" to be the full value.
0
 
LVL 84

Expert Comment

by:ozo
ID: 37731732
fullvalue = bcd_convert(high_digit)<<8+bcd_convert(low_digit);
printf("%04x\n",fullvalue);
0
 

Author Comment

by:frostyourself
ID: 37731766
It's still not working, I added to the printf statement to print the high and low digits separately:

printf("high: %x low: %x full: %04x\n",high_digit,low_digit,full_value);


and this is part of the result:

high: 18 low: 12 full: 0000
high: 18 low: 3 full: 0000
high: 18 low: f8 full: 0018
high: 18 low: 0 full: 1800
high: 18 low: 18 full: 0018
0
 
LVL 84

Accepted Solution

by:
ozo earned 2000 total points
ID: 37731773
//Sorry forgot the parentheses
fullvalue = (bcd_convert(high_digit)<<8)+bcd_convert(low_digit);
0
 

Author Comment

by:frostyourself
ID: 37731795
Thank you, there is just one slight problem:

When there is a single digit (0x00 or 0x03), this happens:

high: c0 low: 3 full: c030
high: f9 low: 0 full: f9c0

Do you know how to fix that? Thank you!!
0
 
LVL 84

Expert Comment

by:ozo
ID: 37731815
bcd_convert(3)==30
bcd_convert(0)==0xc0
if you don't want that, don't bcd_convert
fullvalue = (high_digit<<8)+low_digit;
0
 

Author Closing Comment

by:frostyourself
ID: 37731824
Thank you!
0
 
LVL 84

Expert Comment

by:ozo
ID: 37731908
What is the point of the %10 in high_digit%10 within the sprintf?
To ensure that %d only prints a single digit.
Your original code tried to put %d into a single character, so high_digit_char[2] allocated space for a single character string, with null terminator.
if %d was permitted to print more than a single digit, it would have overflowed the space available.
0

Featured Post

Hire Technology Freelancers with Gigs

Work with freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely, and get projects done right.

Question has a verified solution.

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

How to remove superseded packages in windows w60 or w61 installation media (.wim) or online system to prevent unnecessary space. w60 means Windows Vista or Windows Server 2008. w61 means Windows 7 or Windows Server 2008 R2. There are various …
Whether you’re a college noob or a soon-to-be pro, these tips are sure to help you in your journey to becoming a programming ninja and stand out from the crowd.
The goal of this video is to provide viewers with basic examples to understand how to create, access, and change arrays in the C programming language.
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…

721 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