10.3: Programming Errors
Exam Board:
Eduqas / WJEC
Specification:
2020 +
Syntax Error
A syntax error is a mistake in the grammar or spelling of the program.
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A syntax error will prevent the program from being compiled.
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Examples:
Incorrect Spelling:
pront ("hello")
Incorrect punctuation:
print ("hello"(
Execution (Runtime) Error
An execution error is when the program unexpectedly stops as a result of an operation during execution.
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Examples:
Dividing by zero:
400 / 0
Reading too far in a file:
#There are 50 lines in the file
line = file.readlines( )
print ( line [100] )
Logical Error
Linking Error
A logical error is a mistake made by the programmer - the program still works but displays the wrong output.
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Examples:
Truncation Error
Rounding Error
A linking error occurs when a compiler can’t find a sub procedure (e.g. the random library in Python) that has been used.
The programmer might have declared it incorrectly or forgotten to link (import) it.
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Examples:
Spelling an import command incorrectly:
import ramdon
number = random.randint(1,10)
Requesting a function without linking:
number = random.randint(1,10)
Incorrect calculation:
total = num1 - num2
print (total)
Incorrect variable printed:
age = 16
name = "Steve"
print ("Nice to meet you" , age)
A rounding error is when the program rounds a real number to a fixed number of decimal places.
This results in losing some value as the number becomes less accurate.
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Examples:
Rounding up:
80.87 = 80.9 (Inaccurate by 0.03)
Rounding down:
63.4 = 63 (Inaccurate by 0.4)
A truncation error is when the program truncates a real number to a fixed number of decimal places.
This results in losing some value as the number becomes less accurate.
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Examples:
Truncation to 2 decimal places:
92.13787 = 92.13 (Inaccurate by 0.00787)
Truncation to 1 decimal place:
25.199876 = 25.1 (Inaccurate by 0.099876)
Questo's Questions
10.3 - Programming Errors:
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1. Describe and give an example of each type of error:
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a. Syntax Error [3]
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b. Execution (Runtime) Error [3]
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c. Logical Error [3]
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d. Linking Error [3]
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e. Rounding Error [3]
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f. Truncation Error [3]
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2. State the error that will occur for each scenario: [1 each]
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a. A command word (such as for or print) has been misspelt.
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b. The average speed is 120.3856 but only 120.3 is displayed.
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c. The cost of a meal is £47 but £40 is displayed.
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d. A program uses a subroutine that has not been imported.
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e. The height of a dog is 33.38cm but 33.4cm is displayed.
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f. The user wants to read line 9 of a file that only has 6 lines.
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g. The user's age is printed instead of their name.
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h. The programmer has typed print("hello"(
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i. A number is divided by 0.
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j. The program is asked to generate a random number but 'import random' has not be written.