Menu
How should the try() function be modified (and it's call) to get the output as 11 from the program below?
#include <stdio.h>
/* declare try() here */
int main(void)
{
int x = 10;
try(); /* Call can change */
printf("%d\n", x);
return 0;
}
void try() /* Signature can change */
{
/* how to change x here?? */
}
472
Any variable changes made within a function are local to that function. A calling function's variables are not affected by the actions of a called function.
Functions can access global variables and modify them. Modifying global variables in a function is considered poor programming practice. It is better to send a variable in as a parameter (or have it be returned in the 'return' statement).
Use of “global†keyword to modify global variable inside a function. If your function has a local variable with same name as global variable and you want to modify the global variable inside function then use 'global' keyword before the variable name at start of function i.e.
To change the value of x from within a function, have try() take a pointer to the variable and change it there.
e.g.,
void try(int *x)
{
*x = 11;
}
int main()
{
int x = 10;
try(&x);
printf("%d",x);
return 0;
}
The other answers are correct. The only way to truly change a variable inside another function is to pass it via pointer. Jeff M's example is the best, here.
If it doesn't really have to be that exact same variable, you can return the value from that function, and re-assign it to the variable, ala:
int try(int x)
{
x = x + 1;
return x;
}
int main()
{
int x = 10;
x = try(x);
printf("%d",x);
return 0;
}
Another option is to make it global (but don't do this very often - it is extremely messy!):
int x;
void try()
{
x = 5;
}
int main()
{
x = 10;
try();
printf("%d",x);
return 0;
}
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
