Is there any way of protecting a variable for being modified at runtime in C? -

i wondering if there way of protecting variable being modified once initialized (something "constantize" variable @ runtime ). example:

#include <stdio.h> #include <stdlib.h>  int main(void) {     int v, op;     scanf( "%d", &op );     if( op == 0 )         v = 1;     else         v = 2; // here transform v constant...     .     . // ...and attempt modify v yields error.     .     .     return exit_success; } 

you can make result of input const this:

int func() {     int op = 0;     scanf( "%d", &op );     if( op == 0 )         return 1;     else         return 2; }  int main() {     const int v = func();     // ... } 

nb. of course, there no way prevent undefined behaviour happening later in program appears change v (since undefined behaviour can, definition, have effect).