vault backup: 2024-11-01 13:28:59

education/software development/ECE1400/(not) Chapter 11 Exercises.md

@@ -0,0 +1,20 @@
+1. Suppose that the following declarations are in effect:....
+	a. `14`
+	b. `34`
+	c. `4`
+	d. `true`
+	e. `false`
+
+2. Suppose that `high`, `low`, and `middle` are all pointer variables of the same type, and the `low` and `high` point to elements of an array. Why is the following statement illegal, and how could it be fixed?
+```c
+middle = (low + high) / 2
+```
+The above statement is illegal because you can't add an `int *` to an `int *`. The below operation is legal because you can perform pointer subtraction, and because `low` is defined on the left hand side of the equation, then adding a long to a pointer is valid.
+```c
+middle = low + (high - low) / 2;
+```
+
+3. What will be the contents of the `a` array after the following statements are executed?
+```c
+{10, 9, 8, 7, 6, 5, 4, 3, 2, 1}
+```

education/software development/ECE1400/Chapter 11 Exercises.md

@@ -1,20 +1,30 @@
-1. Suppose that the following declarations are in effect:....
+> 1. If `i` is a variable and `p` points to `i`, which of the following expressions are aliases for `i`?
-	a. `14`
-	b. `34`
-	c. `4`
-	d. `true`
-	e. `false`
 
-2. Suppose that `high`, `low`, and `middle` are all pointer variables of the same type, and the `low` and `high` point to elements of an array. Why is the following statement illegal, and how could it be fixed?
+a. `*p`
-```c
+g. `*&i`
-middle = (low + high) / 2
+
-```
+> 2. If `i` is an `int` variable and `p` and `q` are pointers to `int`, which of the following assignments are legal?
-The above statement is illegal because you can't add an `int *` to an `int *`. The below operation is legal because you can perform pointer subtraction, and because `low` is defined on the left hand side of the equation, then adding a long to a pointer is valid.
+
-```c
+e. `p = *&q;`
-middle = low + (high - low) / 2;
+f. `p = q;`
-```
+i. `*p = *q`
+
+> 3. The following function supposedly computes the sum and average of the numbers in the array `a`, which has length `n`. `avg` and `sum` point to the variables that the function should modify, unfortunately the function contains several errors, find and correct them.
 
-3. What will be the contents of the `a` array after the following statements are executed?
 ```c
-{10, 9, 8, 7, 6, 5, 4, 3, 2, 1}
+void avg_sum(double a[], int n, double *avg, double *sum)
+{
+int i;
+
+// This was assigning a pointer to a float,
+// the dereference operator was missing
+*sum = 0.0;
+for (i = 0; i < n; i++)
+	// This wasn't increasing the value
+	// `sum` points to, it was modifying the address stored in the pointer
+	(*sum) += a[i];
+// Missing dereference operators
+*avg = *sum / n;
+
+}
 ```