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  1. #include<stdio.h>
  2. #include<stdint.h>
  3. #include<float.h>
  4.  
  5. int main(){
  6.  
  7.    // 以下是 0.00390625 二進位表示(IEEE 754)
  8.    char *str = "0011111101110000000000000000000000000000000000000000000000000000";
  9.  
  10.    double b = 0;
  11.  
  12.    uint64_t *ptr = (uint64_t*)&b;
  13.  
  14.    int i;
  15.  
  16.    for(i = 0; i <= 63; ++i){
  17.       *ptr |= ((uint64_t)1 << (63 - i)) * (str[i] - '0');
  18.    }
  19.  
  20.    printf("%.*f\n",DBL_DIG,b);
  21.  
  22.    return 0;
  23. }
Success #stdin #stdout 0s 16064KB
comments (?)
stdin 
Standard input is empty
stdout 
0.003906250000000
https://ideone.com/HgHkWM
language:
C++ (gcc 8.3)
created:
8 years ago
visibility:
public

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