Thread: Get Exponent of Float

  1. #16
    Registered User
    Join Date
    Sep 2020
    Posts
    425
    Quote Originally Posted by ZTik View Post
    The problem to solve was to avoid using Math header, library function and the shift-mask operators.
    In that case the only option was to use the division and the remainder % operators.
    Or just use addition...

    Code:
    #include <stdio.h>
    int main(int argc, char *argv[]) {
       float f;
       int x;
       int e = 0;
    
    
       if(sizeof(int) != 4 || sizeof(float) != 4) {
         printf("Ints are of wrong size\n");
         return 0;
       }
    
    
       printf("Enter value: ");
       scanf("%f",&f);
       printf("Value is %f\n",f);
       x = *((int *)&f);
    
    
       x += x; e = (x < 0 ? e*2+1 : e*2);
       x += x; e = (x < 0 ? e*2+1 : e*2);
       x += x; e = (x < 0 ? e*2+1 : e*2);
       x += x; e = (x < 0 ? e*2+1 : e*2);
       x += x; e = (x < 0 ? e*2+1 : e*2);
       x += x; e = (x < 0 ? e*2+1 : e*2);
       x += x; e = (x < 0 ? e*2+1 : e*2);
       x += x; e = (x < 0 ? e*2+1 : e*2);
    
    
       e -= 127;  // Remove exponent bias
       printf("e is %i\n",e);
    }

  2. #17
    Registered User
    Join Date
    May 2021
    Posts
    17
    For now I will stick to the division implementation, the addition one is efficient.

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