Final answer:
The function call calcroute(2, 3) results in a compile error because the third parameter 'z' is missing and does not have a default value set. Parameters with default values must be specified at the end of the parameter list.
Step-by-step explanation:
The student's question relates to a function declaration in programming, specifically concerning default parameter values in C++ functions. When the programmer defines the function with int calcroute(int x = -1, int y, int z), they are providing a default value for the first parameter 'x' only. This means that if the function is called without specifying the argument for 'x', it will automatically take the value of -1. However, the call calcroute(2, 3) specifies the first two parameters, and since default parameters must be the trailing parameters, this call will result in a compile error because the third parameter 'z' has not been provided and does not have a default value. A correct call to this function with two arguments would only be possible if the default value was assigned to the last parameter, for example, 'z'.