Can't find the reason why value stored to 'delta' isn't read

Question

While analyzing can't seem to avoid the value stored to 'delta' not being read... what part of my loop isn't working and why?

#include <stdio.h>
#include <math.h>
int main()
{
    float a, b, c;
    float delta;
    printf("a=");
    scanf("%f", &a);
    printf("b=");
    scanf("%f", &b);
    printf("c=");
    scanf("%f", &c);
    float x, x1, x2;
    delta=((b*b)-(4*a*c));
    if("delta==0")
    {
        x=((-b)/(2*a));
        printf("x=%f \n", x);
    }
    else if("delta>0")
    {
        x1=((-b+sqrt(delta))/(2*a));
        x2=((-b-sqrt(delta))/(2*a));
        printf("x1=%f i x2=%f \n", x1, x2);
    }
    else printf("Nie ma w zbiorze liczb rzeczywistych rozwiazania tego rownania.\n");
    return 0;
}

do not put your if - condition into ". Be wary of FLOAT and == comparison. use `if(delta == 0)` and `if (delta>0)`. Using a debugger, setting a breakpoint would have told you as much... — Patrick Artner, Nov 11 '17 at 17:30
`if("delta==0")` is always true because you're testing the pointer on a string literal against 0. should be ` if(delta==0)` — Jean-François Fabre, Nov 11 '17 at 17:32
`if("delta==0")`? That's a ***string*** you put in the condition, it will always be "true". Did you mean `if(delta==0)` (without the quotes)? — Some programmer dude, Nov 11 '17 at 17:32
Float to 0 comparison: https://stackoverflow.com/questions/19837576/comparing-floating-point-number-to-zero its c++ but the reasons are same. — Patrick Artner, Nov 11 '17 at 17:32
testing against string also explains why you're getting a warning against `delta` not being read — Jean-François Fabre, Nov 11 '17 at 17:34

score 0 · Accepted Answer · answered Nov 11 '17 at 17:39

1st thing, if("delta==0") inside "" whatever is present that will be treated as a address so if(address) means true, remove the double quotation.

if(delta==0)
    // some code
 else if (delta > 0)
    // some code

2nd thing, you are comparing(==) a float & an integer, so be aware of behaviour of comparing different operands.

Can't find the reason why value stored to 'delta' isn't read

1 Answers1