What's wrong with my if loop??

[mingke]

Hi...

So I have problem with my if condition..I don't know what's wrong but it keeps resulting the wrong answer....

So here's the part of my code I have problem with:

 
 for (i=0; i<size2; i++){          
      for (k = 0; k < point3[i]; k++){       
           for (a=0;a<b[i][k];a++){
              if (90<sudut [i][k][a]<=180){
                teta[i][k][a]=180-sudut[i][k][a]; 
              }  
              else{          
                if (180<=sudut [i][k][a]<270){
                   teta[i][k][a]=sudut[i][k][a]-180;
                }
                else {
                     if (270<=sudut [i][k][a]<360){
                        teta[i][k][a]=360-sudut[i][k][a]; 
                     }
                     else {
                          if (0<=sudut[i][k][a]<90){
                             teta[i][k][a]=sudut[i][k][a];
                          }
                     }
                }
              }        
 
              printf ("[%d][%d][%d]=%f\t%f\n",i,k,a,sudut[i][k][a],teta[i][k][a]);
 
           }
      }
    } 
 

and some of the result is:( I edited it for make it easier to see)

sudut [0][0][0] = 53.157051
teta [0][0][0] = 126.842949

sudut [0][0][1] = 206.000000
teta[0][0][1] = -26.000000

sudut[0][0][4] =341.555695
teta[0][0][4] = -161.555695

sudut [0][1][0] =127.272743
teta [0][1][0] = 52.727257

All of the result is wrong, I just show some because it is so many. I'm sorry...


P.S: if I change the order of the conditions, only the first condition will be result the right answers.

Could you tell me, where I did wrong?
Thank you for your help....

[Banfa]

You can not write a conditional of the form a <= b < c. It doesn't have the meaning you think it is evaluated as (a <= b) < c. Since the output of (a <= b) is 0 or 1 if c > 1 (always in your case) the condition is always true.

Look at this test program

#include<stdio.h>
 
int main()
{
    int i;
 
    for (i=0; i<10; i++)
    {
        printf ("%d: %d %d\n",i, (4<i<=8), (4<i && i<=8));
    }
 
    return 0;
}
 

Also your code would lay out better if your made use of else if rather than else { if ... }

i.e. this

if (...){
    ...
}  
else if (...){
    ...
}
else if (...){
    ...
}
else if (...){
     ...
}        
 

instead of this

if (...){
    ...
}  
else{          
    if (...){
        ...
    }
    else {
         if (...){
            ...
         }
         else {
              if (...){
                 ...
              }
         }
    }
}        
 

P.S. if is not a loop

[mingke]

Thank you for correcting my mistake and my codes...

It's working fine now...