What error causes an undeclared identifier?

Answer 1

Undeclared identifier errors occur in statically typed languages where a name is used before it is declared. For example:

void f (void) {

x = 42; /* error */

}

To fix this error, the name, x, must be declared before it can be initialised with a value:

void f (void) { int x;

x = 42; /* ok */

}

Alternatively, we can combine the declaration and the initialisation:

void f (void) {

int x = 42; /* ok */

}