Explanation:
In C/C++, when you encounter the error message “expression preceding parentheses of apparent call must have (pointer-to-) function type”, it means that you are attempting to call a function on an expression that does not have a function type or a pointer to a function type.
In order to call a function, the expression preceding the parentheses must be a function or a function pointer. If it is neither, you will get this error message.
Example 1:
int x = 5;
x(); // Error: expression preceding parentheses of apparent call must have (pointer-to-) function type
In the above example, the variable ‘x’ is of type ‘int’, which is not a function or a function pointer. Therefore, attempting to call it as if it were a function will result in the mentioned error.
Example 2:
int add(int a, int b) {
return a + b;
}
int multiply(int a, int b) {
return a * b;
}
int main() {
int num1 = 5;
int num2 = 10;
int result = add(num1, num2); // Correct usage of function call
int product = multiply(num1, num2); // Correct usage of function call
return 0;
}
In the above example, we have two functions ‘add’ and ‘multiply’. The expressions ‘add’ and ‘multiply’ have function type, so they can be called as functions. We pass the arguments ‘num1’ and ‘num2’ to these functions to get the desired results.