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Grade 8 Computer Science — Procedures, and calling them

Read a program that gives a block of lines a name, and say what runs, when, and how many times.

Name: ________________________

1.The named block below is called twice. How many numbers does it print?
```
def show():
    print(1)
    print(2)

show()
show()
```

2.A loop calls a block that calls another block. How many numbers does it print?

def inner():
    print(1)

def outer():
    inner()
    inner()

for n in range(1, 5):
    outer()

3.A procedure whose body is a single printing line is used in five different programs. Match each way of using it to how many times its body runs.
- Defined but never called
- Called once at the end of the program
- Called inside a loop over range(1, 6)
- Called twice, and again inside a loop over range(1, 5)
- Called inside a loop over range(1, 3) that itself sits inside a loop over range(1, 5)
- 1
- 8
- 6
- 0
- 5
4.One of these four lines never runs at all. Which one?
```
def alpha():
    print(1)

def beta():
    print(2)

alpha()
print(3)
```
- a) The line printing 1
- b) The line calling alpha
- c) The line printing 3
- d) The line printing 2
5.A program has a procedure called show. Sort each of these by whether it makes the body of show run.
Groups: Makes the body run · Does not make the body run
- Writing show() on a line of its own
- Writing show() as the last line of the program
- Writing show() inside a procedure that is never called
- Writing def show(): with lines indented underneath it
- Writing show() inside a loop that goes round three times
6.Read this program from the top down. How many numbers does it print?
```
def show():
    print(5)
```
- a) 1
- b) 5
- c) It cannot be run at all
- d) 0
7.Follow this code by hand. How many times does the line printing 3 run?
```
def step():
    print(3)

for n in range(1, 5):
    step()
```
8.One line prints before the call is reached. How many numbers does it print?
```
def show():
    print(7)

print(0)
show()
```

Answer key — Grade 8 Computer Science — Procedures, and calling them

1. 4
2. 8
3. Defined but never called → 0; Called once at the end of the program → 1; Called inside a loop over range(1, 6) → 5; Called twice, and again inside a loop over range(1, 5) → 6; Called inside a loop over range(1, 3) that itself sits inside a loop over range(1, 5) → 8
4. d) The line printing 2
5. Writing show() on a line of its own → Makes the body run; Writing def show(): with lines indented underneath it → Does not make the body run; Writing show() inside a loop that goes round three times → Makes the body run; Writing show() inside a procedure that is never called → Does not make the body run; Writing show() as the last line of the program → Makes the body run
6. d) 0
7. 4
8. 2