CODEWITHSUNDEEP
cconditional-statements
user682765
user682765

Reputation: 1229

Conditional checks for different variables

I have a function which sets a variable based on another variable.

if(!button_x.on)
   button_x.on = 1;
if(!button_y.on)
   button_y.on = 1;
if(!button_z.on)
   button_z.on = 1;
.
.
.

If it is x, y, z, …. is determined only at runtime. Having multiple such conditions for various(100s) different cases does not look good. Is there a better way to go about this in C?

EDIT: I should have better framed my example above.

if (!structureA.visited)            
    visit_structureA(); // does some operation
if (!structureB.visited)            
visit_structureB();
if (!structureC.visited)            
visit_structureC();

. . .

The number of structures and the name of the structure is not known at compile time. But the structure names follow a specific pattern shown above. It is known only at runtime. I tried using macros something like:

#define VISIT(str) \
    if (!structure##str.visited) \
        visit_structure##str();

//In the function:
// str = 'known at runtime' 
  VISIT(str);

But this would not work for obvious reason that preprocessor directives are replaced during compile time and not runtime. I am not sure if there is a better way for this?

Upvotes: 0

Views: 98

Answers (2)

Nathan Wiebe
Nathan Wiebe

Reputation: 802

In C, the following condition:

if (!x)
  x = 1;

is equivalent to:

x = 1;

if the variable is boolean (on/off), which I assume is the case if we are talking about buttons.

Upvotes: 1

MByD
MByD

Reputation: 137282

In your example, you set a variable value according to the same variable, not another one, if this is the case, and you want to change it from 0 to 1 and vice versa, you can do it without condition:

button_x.on = !button_x.on;

If you have many of those with the same idea of behavior, consider using array and itertating it.

Upvotes: 1

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