Year 11 Computing — Going through a file line by line

1.The numbers saved in this file are added up as the loop meets them. What does the program print?

f = open("marks.txt", "w")
f.write("8\n3\n6\n")
f.close()
total = 0
f = open("marks.txt", "r")
for line in f:
    total = total + int(line)
f.close()
print(total)

2.The file this loop is given has nothing written in it at all. What does the program print?

f = open("empty.txt", "w")
f.write("")
f.close()
total = 0
f = open("empty.txt", "r")
for line in f:
    total = total + int(line)
f.close()
print(total)

3.This loop prints as it goes rather than keeping anything back. What is the last number it prints?

f = open("steps.txt", "w")
f.write("3\n5\n2\n")
f.close()
f = open("steps.txt", "r")
for line in f:
    print(int(line) * 10)
f.close()

4.A loop over an open file is written as "for line in f:". What does line hold on each trip round?

• a) One character of the file
• b) One line of the file, as a piece of writing
• c) The number of the line, counting from 0
• d) The whole file, all at once

5.This loop keeps hold of the largest number it has seen so far. What does the program print?

f = open("temps.txt", "w")
f.write("14\n39\n22\n")
f.close()
best = 0
f = open("temps.txt", "r")
for line in f:
    if int(line) > best:
        best = int(line)
f.close()
print(best)

6.A program adds up the numbers in a file, one line at a time. Someone then adds one more line to the file, holding 5, and the program is run again without being changed. What is different?

• a) The loop makes one more trip, and the total is 1 larger
• b) The total is 5 larger, but the loop makes the same number of trips as before
• c) The loop makes one more trip, and the total is 5 larger
• d) Nothing, because the program was not changed

7.A decision inside this loop lets only some of the lines reach the counter. What does the program print?

f = open("sales.txt", "w")
f.write("12\n30\n5\n22\n")
f.close()
big = 0
f = open("sales.txt", "r")
for line in f:
    if int(line) > 20:
        big = big + 1
f.close()
print(big)

8.Each of these files is read line by line and its numbers added into a total. Put the files in order of the total each one gives, smallest first.

• "1\n1\n1\n1\n"
• "2\n3\n"
• "6\n8\n"
• "9\n"