Can you parse integers?

look up "sprintf" in MSDN - it is your friend.

#include <string>
#include <sstream>

template<class T>
string ToString( const T& value )
{
  std::ostreamstring oss;
  oss << value;
  return oss.str();
}

string str = ToString( 100 );

assert( str[0] == ''1'' );
assert( str[1] == ''0'' );
assert( str[2] == ''0'' );

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Go Go Go Go Go Fruny.. it''s your birthday.. we''re gonna pary like it''s your..

.lick

Why not just use:

char* score[5];
int currentScore = 100;

itoa( score, currentScore, 10 );


then you have a char array with the score.

score[0] = ''1'' etc

Pfff, Fruny. Use templated std::basic_string and std::basic_ostringstream (character traits). It makes for a more generic function, for example you can use std::wstring with it.

See boost::lexical_cast.

Does that mean that it's my birthday now?

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[edited by - Lektrix on August 27, 2003 12:24:07 PM]

Yes! This is what you do:



int I = 100;
BYTE *HackI = &I



Now you can access each byte!


Hey, don''t forget to visit my page... by clicking here!

That itoa one sounds promising. However, I need it in int form so I can use the value to index into my array of numbers, i.e. 100 would index into numbers[1], numbers[0] and numbers[0]. I guess I''ll have to convert from char to int again. Unless there is a more efficient way. Is there?

char strNum[10];
char* chPtr = strNum;
int n = ...

ltoa(n, strNum, 10);
while(chPtr) {
int nDigit = (int)(*chPtr - ''0'');
// do something with nDigit
++chPtr;
}

Special handling is needed for minus signs...

quote:

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Original post by Billy Lee
That itoa one sounds promising. However, I need it in int form so I can use the value to index into my array of numbers, i.e. 100 would index into numbers[1], numbers[0] and numbers[0]. I guess I''ll have to convert from char to int again. Unless there is a more efficient way. Is there?

---

100 % 10 == 0.
(100/10)%10 == 0.
((100/10)/10)%10 == 1.

So, in general:

int score = 100;
// ...

int ones = score % 10;
score = score / 10;
int tens = score % 10;
score = score / 10;
int hundreds = score % 10;

Of course, at this point, score is meaningless, so you probably want to do all of this on a copy, but you get the point.

-Odd the Hermit

quote:

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Original post by Odd the Hermit
100 % 10 == 0.
(100/10)%10 == 0.
((100/10)/10)%10 == 1.

---

Not bad. Unfortunately this will make scores like 5 come out as 005, but you could have special handling for that if need be (or maybe that''s even acceptable). Also, negative scores will require special handling.

quote:

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Original post by rypyr
Not bad. Unfortunately this will make scores like 5 come out as 005, but you could have special handling for that if need be (or maybe that's even acceptable). Also, negative scores will require special handling.

---

True; perhaps a more robust version would be:

int score;
// ...

bool negative = false;
int ones=0, tens=0, hundreds=0;
if( score < 0 )
   {
   negative = true;
   score = -score;
   }
if( score > 0 )
   {
   ones = score % 10;
   score = score / 10;
   if( score > 0 )
      {
      tens = score % 10;
      score = score / 10;
      if( score > 0 )
         hundreds = score % 10;
      }
   }

Of course, that's an "off the top of my head" implementation, so I'm sure the code could be made a bit cleaner. Still, this will work for any score from -999 to 999, without the overhead of converting to a string and back. (Note: division does have some inherent slowness, but I think it's still faster than converting to/from a string; haven't tested this.) Expanding to handle bigger ranges of scores should be obvious.

-Odd the Hermit

EDIT: realized that I'd gone slightly overboard with the copy/paste.

[edited by - Odd the Hermit on August 28, 2003 11:08:13 AM]

Thanks dudes, that works. My score is always positive so I don''t need to take account of negative numbers.

Jeez, haven''t you people ever heard of the modulus operator?! For example the first digit is x % 10. Then the second is (x % 100) - the first digit; and so on.

atoi( ) does this perfectly... no need for any hacks.

quote:

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Original post by Hawkeye3
atoi( ) does this perfectly... no need for any hacks.

---

Modulus isn''t a hack, it''s simply basic arithmetic that ALL programmers SHOULD know.

Are you using the digits to index a font-character array?
If so, then itoa is the best way. It''s efficent and yields the result you want, 5 is "5" not "005".

To index your array from the result of itoa:

char buf[32];
itoa(buf, x, 10);
for(char* c=&buf[0]; *c!=0; ++c)
   {
   int d = *c - ''0'';
   assert(d>=0 && d<=9);
   number[d];
   }

It''s not exactly a hard function to write if it''s missing.

Using stringstream would result in memory (de)allocation, perhaps multipl allocations, per string displayed.