itoa problem?

[news.hku.hk]

Excuse me, i write the following function to add comma for integers
but the unix server said:

In function `class string comma(int)':
implicit declaration of function `int itoa(...)'
________________________________

string comma(int a){
char to_string[50];
string s_a = itoa(a, to_string, 10);

if (a>1000000000){
s_a.insert(s_a.length()-9, ",");
s_a.insert(s_a.length()-6, ",");
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else if (a>1000000){
s_a.insert(s_a.length()-6, ",");
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else if (a>1000){
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else return (s_a);
}
_____________________________
do i use itoa wrongly or i miss anything, i've already include the header
#include <cstdlib>

Thanks

[Mike Wahler]

"news.hku.hk" <bi******@hkusua.hku.hk> wrote in message
news:40********@newsgate.hku.hk...

Excuse me, i write the following function to add comma for integers
but the unix server said:

In function `class string comma(int)':
implicit declaration of function `int itoa(...)'
________________________________

string comma(int a){
char to_string[50];
string s_a = itoa(a, to_string, 10);

if (a>1000000000){
s_a.insert(s_a.length()-9, ",");
s_a.insert(s_a.length()-6, ",");
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else if (a>1000000){
s_a.insert(s_a.length()-6, ",");
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else if (a>1000){
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else return (s_a);
}
_____________________________
do i use itoa wrongly or i miss anything, i've already include the header
#include <cstdlib>

There is no such function 'itoa()' in standard C++.
If your imlementation provides one, you'll need to
#include the header which declares it, and follow
the usage instructions given in its documentation.

Since this newsgroup only discusses standard C++,
nonstandard functions such as 'itoa()' are not
topical here.

-Mike

[Julie]

"news.hku.hk" wrote:

Excuse me, i write the following function to add comma for integers
but the unix server said:

In function `class string comma(int)':
implicit declaration of function `int itoa(...)'
________________________________

string comma(int a){
char to_string[50];
string s_a = itoa(a, to_string, 10);

if (a>1000000000){
s_a.insert(s_a.length()-9, ",");
s_a.insert(s_a.length()-6, ",");
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else if (a>1000000){
s_a.insert(s_a.length()-6, ",");
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else if (a>1000){
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else return (s_a);
}
_____________________________
do i use itoa wrongly or i miss anything, i've already include the header
#include <cstdlib>

Thanks

itoa() is not part of the standard C++ language. So, you will either have to
figure out the specifics of itoa on your platform/compiler, or abandon it
altogether and use something like std::ostringstream:

std::ostringstream tc;
tc << a;
string s_a = tc.str();

Aside from that, there are better ways to insert thousands separators into a
string -- if you would like other ideas, please post back.

[marbac]

news.hku.hk schrieb:

do i use itoa wrongly or i miss anything, i've already include the header
#include <cstdlib>

i searched through the cstdlib (and stdlib.h) and there seems to be no
function called itoa. Maybe it is also not defined in your lib version.

regards marbac

[news.hku.hk]

Of course, i want better and faster method, i know my method is not good
Thanks a lot
"Julie" <ju***@nospam.com> wrote in message
news:40***************@nospam.com...

"news.hku.hk" wrote:

Excuse me, i write the following function to add comma for integers
but the unix server said:

In function `class string comma(int)':
implicit declaration of function `int itoa(...)'
________________________________

string comma(int a){
char to_string[50];
string s_a = itoa(a, to_string, 10);

if (a>1000000000){
s_a.insert(s_a.length()-9, ",");
s_a.insert(s_a.length()-6, ",");
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else if (a>1000000){
s_a.insert(s_a.length()-6, ",");
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else if (a>1000){
s_a.insert(s_a.length()-3, ",");
return (s_a);
}
else return (s_a);
}
_____________________________
do i use itoa wrongly or i miss anything, i've already include the header #include <cstdlib>

Thanks
itoa() is not part of the standard C++ language. So, you will either have

to figure out the specifics of itoa on your platform/compiler, or abandon it
altogether and use something like std::ostringstream:

std::ostringstream tc;
tc << a;
string s_a = tc.str();

Aside from that, there are better ways to insert thousands separators into a string -- if you would like other ideas, please post back.

[John Harrison]

"news.hku.hk" <bi******@hkusua.hku.hk> wrote in message
news:40********@newsgate.hku.hk...

Excuse me, i write the following function to add comma for integers
but the unix server said:

In function `class string comma(int)':
implicit declaration of function `int itoa(...)'
________________________________

string comma(int a){
char to_string[50];
string s_a = itoa(a, to_string, 10);

itoa is non-standard, a simple replacement would be sprintf.

#include <stdio.h> // or <cstdio>

string comma(int a) {
char to_string[50];
sprintf(to_string, "%d", a);
string s_a = to_string;
...

john

[Julie]

"news.hku.hk" wrote:

Of course, i want better and faster method, i know my method is not good
Thanks a lot

Look into facets and numpunct.

[Siemel Naran]

"news.hku.hk" <bi******@hkusua.hku.hk> wrote in message

Of course, i want better and faster method, i know my method is not good

See the thread "how to display 12345 as 12,345 ??" which finished a few days
ago on this newsgroup, in particular Dietmar's answer.