got a problem with variables and setting values

here's my code I wanted to make the code parametric so I needed
various possible  values but I hit a snag.

bearings=10;
//for smooth rods put in diameter in mm
smooth=10;
// for z-screw 5 for 5mm 8 for 8mm and 8.5 for acme
z_screw=5;
// for mechanical z=probe use 1 for yes 0 for no 2 for i3 type probe
z_probe = 1;
wall=4;
lmd=1;
lml=1;
echo(bearings,smooth,z_screw);
if (bearings==10){lmd=19.05;lml=29.05;}
   echo(lmd,lml);

lmd and lml return 1 even though I thought I was assigning the actual
values with the if statement.




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R. Daniel Borkan
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here's my code I wanted to make the code parametric so I needed
various possible  values but I hit a snag.

bearings=10;
//for smooth rods put in diameter in mm
smooth=10;
// for z-screw 5 for 5mm 8 for 8mm and 8.5 for acme
z_screw=5;
// for mechanical z=probe use 1 for yes 0 for no 2 for i3 type probe
z_probe = 1;
wall=4;
lmd=1;
lml=1;
echo(bearings,smooth,z_screw);
if (bearings==10){lmd=19.05;lml=29.05;}
   echo(lmd,lml);

lmd and lml return 1 even though I thought I was assigning the actual
values with the if statement.

This might well be the most common OpenSCAD question.

OpenSCAD variables... aren't variables.  They're constants, sort of, with the last assignment winning and with inner scopes able to override values from outer scopes.  You can't change them, or at least not exactly, and you especially can't change them inside an "if".

x=1;
echo(x=x);
x=2;
echo(x=x);

produces

ECHO: x = 2
ECHO: x = 2

and

x=1;
echo(x=x);
if (true) {
    x=2;
    echo (x=x);
}
echo (x=x);

produces

ECHO: x = 1
ECHO: x = 2
ECHO: x = 1

For your case here, you need to use the ?: operator to set the right value when you do the initial assignment.

lmd= bearings==10 ? 19.05 : 1;
lml= bearings==10 ? 29.05 : 1;
echo(bearings,smooth,z_screw);
echo(lmd,lml);

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