进制转换

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1.二进制转十进制

#include  <iostream>#include  <string.h>void main(){long int i,len,sum=0;char str[30];printf("\n输入二进制数:\n");gets(str);len=strlen(str);for(i=len-1;i>=0;i--)sum+=(long)(str[i]-'0')<<(len-1-i);printf("%ld\n",sum);system("pause");}

2.获得多少个1

#include <iostream>using namespace std;char *ok(int n,char *b)  {  static int LEN=8*sizeof(int);  for(int i=LEN-1;i>=0;i--,n>>=1)  b[i]=(01&n)+'0';  b[LEN]='\0';  return b;  }  int GetIntCount(string b){int nCount=0;static int LEN=8*sizeof(int); for(int i=0;i<LEN;i++){if(1==b[i]-48)nCount++;}return nCount;}void main()  {  int v=255;  char b[8*sizeof(int)+1];  int i=-1;  string s=ok(v,b);cout<<ok(v,b)<<endl;cout<<GetIntCount(s)<<endl;system("pause");}

#include <iostream>using namespace std;int GetIntCount(int n){char Answer[8*sizeof(int)+1];  static int LEN=8*sizeof(int);for (int i = LEN - 1; i >= 0; i--, n >>= 1)Answer[i] = (01 & n) + '0';Answer[LEN] = '\0';string Str = Answer;int nCount=0;for(int i=0;i<LEN;i++){if(1==Str[i]-48)nCount++;}return nCount;}void main()  {  cout<<GetIntCount(7)<<endl;system("pause");}

3.十进制转二进制

#include <iostream>using namespace std;char *ok(int n,char *b)  {  static int LEN=8*sizeof(int);  for(int i=LEN-1;i>=0;i--,n>>=1)  b[i]=(01&n)+'0';  b[LEN]='\0';  return b;  }  void main()  {  int v[]={7,256};  char b[8*sizeof(int)+1];  int i=-1;  while(++i<sizeof(v)/sizeof(v[0]))  cout<<ok(v[i],b)<<endl;system("pause");}

#include <stdlib.h> #include <stdio.h> int Fuc(int bin){int lln=1;int dec=0 ;while (bin){dec+=bin%10*lln;lln*=2;bin/=10;}return dec;} int main(void) {    int number = 256;     char string[25];   printf("%d\n",number);itoa(number, string, 2);  printf("%s\n",string);   number = atoi(string);  printf("%d\n",Fuc(number));system("pause");return 0;}