Hi.

Just as a learning exercise, I've come up with an implementation of
itoa() without using something like sprintf. However, I can't figure
out how to extend it to deal with negative numbers - any help
appreciated!

char * itoa(int a)
{
#define BUFFSIZE 50

static char str[BUFFSIZE];

int i = sizeof(str) - 1;

do
{
str[--i] = '0' + a % 10;
}
while ((a = a / 10) && i >= 0);

return &str[i];
}

Couple of notes on this.

gareth.p.davies@googlemail.com wrote:

gareth.p.davies@googlemail.com wrote:

MQ wrote:

pete wrote:

MQ wrote:

pete wrote:

sounds like a poor design to me. Simply passing the char array as a
parameter would be neater. This pattern exists for such library
functions as fread()

MQ

pete wrote:

MQ wrote:

Here's one that handles negative numbers:

#define BUFFSIZE 30

#define pc(c) ( 12345 == (*p99++ = c))

char * p99; char s99[BUFFSIZE];

void putd( int aa ){ if( aa > 9 ) putd( aa / 10 ); pc( (char) (aa %
10) + '0' ); }

char * ita( int a ) { p99 = s99; putd( a < 0 ? pc( '-' ) - a : a
);return s99 + pc( '\0' );
}

int main( int argc, char * argv[] )
{ char foo[1000]; int i; char * s; );
for( i = -123; i < 123 ; i ++ ) { s = ita( i ); printf( "%d = '%s'\n",
i, s ); }
gets_s( foo );
return 0;
}