Convert from int to char 1

[oueleric1]

Just starting out programming. I have a book however it's not here right now and i'm in a hurry. Is it possible to change an int variable into a char varaiable? Thanks in advance.

 

[uolj]

If you have a single digit integer, like 6, and you want to convert it to a single character that represents that integer, like '6', then you can simply add the integer to the character '0' since the characters for the digits 0-9 are in order.

int i = 6;
char c = '0' + i;
// now c is '6'.

If you might have a multiple digit number and you want to convert it to its character representation, then you cannot store that in a character, you must store it in a string. To do this conversion you can use a stringstream.

#include <sstream>
#include <string>
// ...
int i = 372;
std::ostringstream ostr;
ostr << i;
std::string s = ostr.str();
// now s is "372".

If you have the integer value of a character and you want to convert it to the actual character, you can just assign it (with a cast).

int i = 65;
char c = static_cast<char>(i);
// now c is 'A'.

 

[ArkM]

Some addition. The last but not least approach: use old good C (sorry, Mr.Stroustrup library (part of C++ Standard):

#include <cstdio>
...
int i = 372;
string std::s;
...
{ // block if you need local buffer...
  char ibuff[24]; // or what else, or use outer char array
  sprintf(ibuff,"%d",i); // use a proper format: "%04d"...
  s = ibuff;
}

No need in awkward ostringstream manipulators (set then don't forget to restore etc), no awkward std:stringstream words at all...

 

[tmiketx]

never convert numbers using knowledge of the ordinal positions of the numeral inside the character set. it would be like upshifting letters by adding & subtracing the biases into the ASCII uppercase/lowercase sequence. use the library conversion routines instead, as they work for all characters sets; the majority of the examples given in response to your question should never be used in production code - and certainly not at performance-review time

 

[uolj]

never convert numbers using knowledge of the ordinal positions of the numeral inside the character set. it would be like upshifting letters by adding & subtracing the biases into the ASCII uppercase/lowercase sequence. use the library conversion routines instead, as they work for all characters sets; the majority of the examples given in response to your question should never be used in production code - and certainly not at performance-review time

Could you be more specific about what is wrong with the examples given. Other than the comment in my third example assuming an ASCII character set, I don't see any problems. Also, what's a library conversion routine for converting an int to a char?

 

[drewdaman]

i would say the easiest way is:

int a = 27;
char * b= new char [50]; //you will have to think about 
                         //the size yourself
itoa(a, b, 10); //b will now contain the value you want
                //as a string

itoa will give you a null terminated string. just make sure you b is large enough.

check out:

http://www.cplusplus.com/ref/cstdlib/itoa.html

 

[cpjust]

itoa() is great, unfortunately it's only on Windows.

 

[ADoozer]

itoa() is great, unfortunately it's only on Windows

this is the microsoft: Visual C++ forum....



If somethings hard to do, its not worth doing - Homer Simpson

 

[chipperMDW]

Even so, portability is a good thing. If you can do so easily, avoiding OS-specific calls -- or at least confining them to a single file -- can make someone else's life substantially easier down the road.

 

[drewdaman]

well.. yeah.. i wasn't aware that this wasn't for a windows platform.. also.. you can't keep rewriting functions that have already been written- you will drive yourself crazy! i would say if you are developing a windows app just go ahead and use it! re-use as much code as possible!

 

[oueleric1]

Thanks alot you guys, i found an easier way around it, i kind of did it the long way the first time, however now i know. Thanks again

 

[cpjust]

if you are developing a windows app just go ahead and use it! re-use as much code as possible!

That would work fine until your company see's that the product is selling well and decides to port it to UNIX...

 

[chipperMDW]

you can't keep rewriting functions that have already been written- you will drive yourself crazy!

Agreed.

But when a portable alternative already exists, and it's no more trouble to use it, you might as well.