Quote:
Original post by kubapl
Hi, I am trying to do calculations to numbers that are to big for int or even __int64. I have just installed boost and configured it with my visual studio. I'm using C++ and spent the last hour trying to find a code snippet showing how to use boost's integers to store large numbers with no luck.
Quote:
Original post by kubapl
The readme is useless as it only talks about the changes in the new version. As far as the installer its unrecognizable... I'm starting to think that I have a linux version ? Is there a .exe out there for vs 2008 pro?
[sourcecode]#include <stdio.h>#include <stdlib.h>#include <string.h>#define size 20class LargeNum{ public: unsigned char data[size]; void add(LargeNum &a){ int remaining = 0; for(int i=0; i<size; i++){ remaining += data + a.data; data = remaining&0xff; remaining >>= 8; } } void sub(LargeNum &a){ int remaining = 0; for(int i=0; i<size; i++){ remaining += data - a.data; data = remaining&0xff; remaining >>= 8; } } void mul(LargeNum &a){ unsigned char temp[size]; for(int i=0; i<size; i++) temp = 0; for(int i=0; i<size; i++){ unsigned int remaining = 0; for(int j=0; j<size-i; j++){ remaining += ((int)data[j])*(int)a.data + temp[i+j]; temp[i+j] = remaining&0xff; remaining >>= 8; } } for(int i=0; i<size; i++) data = temp; } void print(){ int i; for(i=size-1; i>0; i--) if(data) break; printf("0x%x",data); i--; for(;i>=0; i--) printf("%02x", data); printf("\n"); } LargeNum(char *str){ char temp[size*2] = {0}; for(int i=0; i<size*2; i++) temp= '0'; int l = strlen(str); for(int i=0; i<l; i++){ temp[size*2-l+i] = str; } for(int i=0; i<size; i++){ int n = temp[size*2-1-2*i]; int m = temp[size*2-2-2*i]; if(n >= '0' && n <= '9') n -= '0'; else if(n >= 'a' && n <= 'f') n -= 'a'-10; else if(n >= 'A' && n <= 'F') n -= 'A'-10; if(m >= '0' && m <= '9') m -= '0'; else if(m >= 'a' && m <= 'f') m -= 'a'-10; else if(m >= 'A' && m <= 'F') m -= 'A'-10; data = n + 16*m; } } }; int main(void){ LargeNum a("1234"); LargeNum b("4321"); LargeNum c("4000000000000"); LargeNum d("1"); a.print(); printf("+\n"); b.print(); printf("=\n"); a.add(b); a.print(); printf("\n*\n"); c.print(); a.mul(c); printf("=\n"); a.print(); printf("\n-\n"); d.print(); a.sub(d); a.print(); }[/sourcecode]Quote:
Original post by shultays
if you have time you can write your own one, it is not that hard
Quote:
Original post by SiCrane Quote:
Original post by shultays
if you have time you can write your own one, it is not that hard
If it's not that hard then why doesn't your class handle division and think that one minus ten happens to be 0xfffffffffffffffffffffffffffffffffffffff1?
Quote:
Original post by shultays
Maybe not that easy but It won't take more than 3-4 days of programming.
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Original post by s_p_oneil
SiCrane - shultays is being helpful, and IMO your comments and attitude are uncalled for.
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Original post by s_p_oneil
SiCrane - shultays is being helpful, and IMO your comments and attitude are uncalled for.
shultays - If you're interested, you can improve your class a good bit without a lot of effort by adding shift left and right functions. You can then implement a more efficient multiply using shift and add, as well as a fairly efficient division using shift and subtract. If you Google "shift and subtract division", you'll see it's not that bad, and shouldn't take you more than an hour or two once you figure it out.
kubapl - If you just want a quick solution to a specific problem and you're willing to try a scripting language like Python or Ruby, SiCrane's advice could make your life about a hundred times easier. However, if your goal is to master C++, follow everyone else's advice. Figuring out how to deal with third-party libraries will teach you some things, and learning how to implement your own math classes will teach you other things. If you really want to master C++, I recommend you do both. Create a new class based on shultay's, then link in a library like MP and run some performance comparisons between the two.
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