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2 changed files with 16 additions and 46 deletions

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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}
```

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> 1. If `i` is a variable and `p` points to `i`, which of the following expressions are aliases for `i`?
a. `*p`
g. `*&i`
> 2. If `i` is an `int` variable and `p` and `q` are pointers to `int`, which of the following assignments are legal?
e. `p = *&q;`
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.
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
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;
}
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}
```