Programming Forums > Application Development > C++

King · Jan 30th, 2006, 11:51 PM

How can I convert a char[] to int without using atoi?

Jerkstore · Jan 30th, 2006, 11:54 PM

int(variable)

King · Jan 30th, 2006, 11:59 PM

doesnt work

The Dark · Jan 31st, 2006, 12:06 AM

Why would you want to? Perhaps for a programming class?

Think about how you might approach this if you were doing it step by step on paper. One way is to go through each character in the char[] and convert it to an integer value, keeping a running total in an int. Each time you process a new character, multiply the current running total by 10 and add in the integer value of the char.

Give it a go and if you get into trouble, post your code here.

ivan · Jan 31st, 2006, 3:20 AM

Do you want to create your function or only use a different one from atoi()?

sunnypalsingh · Jan 31st, 2006, 4:28 AM

Use strtol function. Its safer than atoi.

DaWei · Jan 31st, 2006, 7:31 AM

Quote:

Q. How can I convert a char[] to int without using atoi?
A. int(variable)

This is the kind of crap answer I'm talking about. Please don't do this. You do neither yourself nor the questioner any good.

King · Jan 31st, 2006, 8:16 AM

I got it working, thanks for the replies

clsk · Jan 31st, 2006, 8:42 AM

If you're using doing this in c++ why are you even using a char array to manage strings of characters?
I recommend you use std::string to manage strings of characters.
To convert integer values that are represented in a string use std::stringstream.

Here's a function I normally use to do this.
You might want to make it inline.

(Toggle Plain Text)

int StringToInt(const std::string& str) // string to int
{
  stringstream l_ss(str);
  int l_rint;
  l_ss >> l_rint; // casting from string to int...

return l_rint;
}

To do the opposite you'd use a output stringstream or std:: ostringstream.

Polyphemus_ · Jan 31st, 2006, 9:38 AM

Quote:

Originally Posted by Jerkstore

int(variable)

I recommend checking what language a question is for, before giving stupid and wrong answers.

Jan 30th, 2006, 11:51 PM	#1
King Professional Programmer Join Date: Jan 2006 Location: Ontario, Canada Posts: 376 Rep Power: 0	Convert char[] to int How can I convert a char[] to int without using atoi? __________________ I am Addicted to Linux!

Jan 30th, 2006, 11:59 PM	#3
King Professional Programmer Join Date: Jan 2006 Location: Ontario, Canada Posts: 376 Rep Power: 0	doesnt work __________________ I am Addicted to Linux!

Jan 31st, 2006, 4:28 AM	#6
sunnypalsingh Programmer Join Date: Dec 2005 Posts: 33 Rep Power: 0	Use strtol function. Its safer than atoi. __________________ The only real valuable thing is intuition. -Albert Einstein

Jan 31st, 2006, 8:16 AM	#8
King Professional Programmer Join Date: Jan 2006 Location: Ontario, Canada Posts: 376 Rep Power: 0	I got it working, thanks for the replies __________________ I am Addicted to Linux!

Jan 31st, 2006, 8:42 AM	#9
clsk Newbie Join Date: Jan 2006 Posts: 13 Rep Power: 0	If you're using doing this in c++ why are you even using a char array to manage strings of characters? I recommend you use std::string to manage strings of characters. To convert integer values that are represented in a string use std::stringstream. Here's a function I normally use to do this. You might want to make it inline. (Toggle Plain Text) int StringToInt(const std::string& str) // string to int { stringstream l_ss(str); int l_rint; l_ss >> l_rint; // casting from string to int... return l_rint; } int StringToInt(const std::string& str) // string to int { stringstream l_ss(str); int l_rint; l_ss >> l_rint; // casting from string to int... return l_rint; } To do the opposite you'd use a output stringstream or std:: ostringstream.

Jan 30th, 2006, 11:54 PM	#2
Jerkstore Newbie Join Date: Dec 2005 Posts: 12 Rep Power: 0	int(variable)

Jan 31st, 2006, 12:06 AM	#4
The Dark Expert Programmer Join Date: Jun 2005 Posts: 852 Rep Power: 4	Why would you want to? Perhaps for a programming class? Think about how you might approach this if you were doing it step by step on paper. One way is to go through each character in the char[] and convert it to an integer value, keeping a running total in an int. Each time you process a new character, multiply the current running total by 10 and add in the integer value of the char. Give it a go and if you get into trouble, post your code here.

Jan 31st, 2006, 3:20 AM	#5
ivan Professional Programmer Join Date: Sep 2005 Location: serbia & montenegro Posts: 484 Rep Power: 4	Do you want to create your function or only use a different one from atoi()?

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Programming Forums > Application Development > C++

Convert char[] to int