why its not correctly working?

Question

#include <stdio.h>
#include <math.h>
#include <conio.h>

int main()

{
    float y;
    float x;
    printf("nubmer x \n");
    scanf("%f", &x);
    if(x<-1.5)
    {
        y=1;
    }
    
    else if(0)
    {
        y=0;
    }
    else if(x=-2)
    {
        y=0;
    }
else if(x>=1)
    {
        y=1;
    }

    else
        y=-2;
   
    printf("y=%f", y);
    getch();
    
}

Answer 1

else if(0) always evaluates to false. Did you mean else if (x == 0)?

else if(x=-2) assigns the value -2 to x. Probably you want to check equality like else if (x == -2).

The x == -2 check must come before the x < -1.5 as -2 is less than -1.5, so the first condition will always be true and y will be set to 1.

Something like this would work:

#include <stdio.h>

int main()
{
    float y;
    float x;
    printf("Number x: ");
    scanf("%f", &x);
    
    if (x == -2.0f)
    {
        y = 0;
    }
    else if (x < -1.5f)
    {
        y = 1;
    }
    else if (x == 0.0f)
    {
        y = 0;
    }
    else if (x >= 1.0f)
    {
        y = 1;
    }
    else
    {
        y = -2;
    }
   
    printf("y = %f\n", y);
    return 0;
}

Answer 2

Well, there are some logical issues with your code, you can try this code to fix the error.

#include <stdio.h>

#include <conio.h>
#include <math.h>

int main()

 {
    float y;
    float x;
    printf("number x \n");
    scanf("%f", &x);

    if (x < -1.5) 

{
        y = 1;
    } 

else if (x == -2) 

{
        y = 0;
    }

 else if (x >= 1) 

{
        y = 1;
    } 

else 

{
        y = -2;
    }

    printf("y = %f\n", y);

    return 0;
}

Thanks