社群資訊
整數的 over- flow
(高顯忠, sjgau4311@gmail.com, 2011-02-08 11:38)
1樓
#if 0
// no= 81920 的時候，
sum <> xs,
xs 是正確的目標答案，33億 左右，超過 +2147483647,
所以，出現 整數 over- flow 的錯誤。
no= 81920
sum= -939483136,
xs= 3355484160
*** Press [Esc] key for Stop! or other key for Continue...
// --------------------------------------------------------
no= 10
sum= 55,
xs= 55
*** Press [Esc] key for Stop! or other key for Continue...
no= 20
sum= 210,
xs= 210
*** Press [Esc] key for Stop! or other key for Continue...
no= 40
sum= 820,
xs= 820
*** Press [Esc] key for Stop! or other key for Continue...
no= 80
sum= 3240,
xs= 3240
*** Press [Esc] key for Stop! or other key for Continue...
no= 160
sum= 12880,
xs= 12880
*** Press [Esc] key for Stop! or other key for Continue...
no= 320
sum= 51360,
xs= 51360
*** Press [Esc] key for Stop! or other key for Continue...
no= 640
sum= 205120,
xs= 205120
*** Press [Esc] key for Stop! or other key for Continue...
no= 1280
sum= 819840,
xs= 819840
*** Press [Esc] key for Stop! or other key for Continue...
no= 2560
sum= 3278080,
xs= 3278080
*** Press [Esc] key for Stop! or other key for Continue...
no= 5120
sum= 13109760,
xs= 13109760
*** Press [Esc] key for Stop! or other key for Continue...
no= 10240
sum= 52433920,
xs= 52433920
*** Press [Esc] key for Stop! or other key for Continue...
no= 20480
sum= 209725440,
xs= 209725440
*** Press [Esc] key for Stop! or other key for Continue...
no= 40960
sum= 838881280,
xs= 838881280
*** Press [Esc] key for Stop! or other key for Continue...
no= 81920
sum= -939483136,
xs= 3355484160
*** Press [Esc] key for Stop! or other key for Continue...
#endif
// ----------------------------------------------
#include <stdio.h>
#include <math.h>
#include <process.h>
#include <conio.h>
#include "sj-01.h"
// ----------------------------------------------
// for time1(), time2()
int main()
{
int no, sum, i;
double xs;
no= 10;
while (no > 0) {
sum= 0;
for (i=1;i<=no;i++) {
sum+= i;
}
xs= (1.0 + no)*(no - 1.0 + 1.0)/2.0;
skip(1);
printf("no= %d \n", no);
printf("sum= %d, \n xs= %.0lf \n", sum, xs);
pause();
no*= 2;
}
return(0);
}// end of main()