Convert int to char*

Convert int to char*

Calle Arnesten

Member #1,356

April 2001

How do I in C++ convert integers to char*?
Say I have a number 123 I want it to be "123".
I searched the forum and what I found was something about sprintf, but that is C, and I also found someone mentioning itoa and _itoa, but I couldn't find those in my gcc compiler.
So is there another way?

lwithers

Member #630

September 2000

You could either write your own routine (which isn't difficult), or you could use the C library's sprintf() (there is nothing wrong with using libc calls in C++).
Here is an example of a function that returns a string class given an integer:
code:#include <string>
#include <stdio.h>
string int_to_string(int i)
{
char buf[100];
usprintf(buf, "%d", i);
return string(buf);
}
Note that I have used usprintf, which is Allegro's Unicode-aware version of sprintf. Also note that the C++ string class can handle the \0 character within strings, since it stores the length separately: this makes it valid to handle Unicode strings with string.

Jason Heim

Member #484

June 2000

careful!
you can get into trouble returning pointers to locally declared variables and arrays. this function would be better off receiving a pointer to a target array and returning nothing:
code:
void int_to_string(int i, char *c){
usprintf(c, "%d", i);
}

of course in this case, it is even better handled by a macro:
code:
#define int_to_string(i, c) usprintf(c, "%d", i)

good luck!

brain21

Member #1,208

December 2000

What about just using the itoa() command?
#include <stdio.h>
#include <string.h>
char string[]="90236";
int num;
num=itoa(string);

Jason Heim

Member #484

June 2000

brain21,

you mean atoi(), which converts the other way

i've never heard of itoa(), not to say that it doesn't exist, but it all probably uses the same routines behind the scenes (although sprintf would obscure it a little). the C reference i have doesn't list itoa(), only atoi().

good luck!

Bob

Free Market Evangelist

September 2000

itoa() is present in DJGPP, but it's listed as non-Ansi, non-Posix, so chances are it won't work on other compilers.

[ May 30, 2001: Message edited by: Bob ]

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- Bob
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