cpp/functions/vowels Source

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Description
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Note: For this exercise, we'll use C++ <tt>string</tt> objects.
To get the kth <tt>char</tt> from a <tt>string s</tt>,
write <tt>s[k]</tt>, like an array.

Complete the method
<tt>int frequency(string haystack, char needle)</tt>
so that it returns the number of times that the character <tt>needle</tt>
occurred in <tt>haystack</tt>. For example <tt>frequency("hello", 'l')</tt>
should return 2.

Then, define a function <tt>vowel_count</tt> that takes a <tt>string</tt>
argument and returns the number of vowels it contains. Assume the vowels are:
a, e, i, o, and u. For example <tt>vowel_count("hello")</tt> should be 2.
Hint: use <tt>frequency</tt>.

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Engine
Choices
json list of string, bool pairs
e.g. [["good", true], ["bad", false]]

Correct answer
Template / Reference solution

Template / Reference solution

#include <iostream>
#include <string>
using namespace std;

// return the number of times that needle occurs in haystack
int frequency(string haystack, char needle) {
int n = haystack.length(); // this is how you get length of C++ string
int result = 0;

// loop to count the occurrences
for (int i=0; i<n; i++) {
if (haystack[i] \[== needle]\) // look at ith character
\[result++;]\
}

return result;
}

// return the number of vowels in the given string
\[
int vowel_count(string text) {
return frequency(text, 'a') + frequency(text, 'e') +
frequency(text, 'i') + frequency(text, 'o') + frequency(text, 'u');
}
]\

Java test suite
See manual

C++ test suite
json list of stdin/args tests
e.g. [{"stdin":"hi", "args":["4", "5"]}, {"stdin":"noargs"}]
to just run once with no input use [{}]

C++ test suite
See manual

[
["check-function", "frequency", "int", ["string", "char"]],
["check-function", "vowel_count", "int", ["string"]],
["call-function", "frequency", ["\"hello\"", "'l'"]],
["call-function", "frequency", ["\"goodbye\"", "'l'"]],
["call-function", "vowel_count", ["\"supercalifragilisticexpialidocious\""]],
["call-function", "vowel_count", ["\"facetious\""]],
["call-function", "vowel_count", ["\"phhhht\""]]
]

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i.e., just a demo
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json list of flags
e.g. ["-Wno-unused-variable"]

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json list of flags
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e.g. ["-Wno-write-strings"]

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Property	Value
Description html markup shown to student	<b>Note:</b> For this exercise, we'll use C++ <tt>string</tt> objects. To get the <i>k</i>th <tt>char</tt> from a <tt>string s</tt>, write <tt>s[k]</tt>, like an array. <p> Complete the method <tt>int frequency(string haystack, char needle)</tt> so that it returns the number of times that the character <tt>needle</tt> occurred in <tt>haystack</tt>. For example <tt>frequency("hello", 'l')</tt> should return 2. <p> Then, define a function <tt>vowel_count</tt> that takes a <tt>string</tt> argument and returns the number of vowels it contains. Assume the vowels are: a, e, i, o, and u. For example <tt>vowel_count("hello")</tt> should be 2. Hint: use <tt>frequency</tt>.
Epilogue html markup shown when solved	remove
Public permissions	remove
Remarks Comments, history, license, etc.	remove
Engine
Choices json list of string, bool pairs e.g. `[["good", true], ["bad", false]]`
Correct answer
Template / Reference solution
Template / Reference solution	#include <iostream> #include <string> using namespace std; // return the number of times that needle occurs in haystack int frequency(string haystack, char needle) { int n = haystack.length(); // this is how you get length of C++ string int result = 0; // loop to count the occurrences for (int i=0; i<n; i++) { if (haystack[i] \[== needle]\) // look at ith character \[result++;]\ } return result; } // return the number of vowels in the given string \[ int vowel_count(string text) { return frequency(text, 'a') + frequency(text, 'e') + frequency(text, 'i') + frequency(text, 'o') + frequency(text, 'u'); } ]\
Java test suite See manual
C++ test suite json list of stdin/args tests e.g. `[{"stdin":"hi", "args":["4", "5"]}, {"stdin":"noargs"}]` to just run once with no input use `[{}]`
C++ test suite See manual	[ ["check-function", "frequency", "int", ["string", "char"]], ["check-function", "vowel_count", "int", ["string"]], ["call-function", "frequency", ["\"hello\"", "'l'"]], ["call-function", "frequency", ["\"goodbye\"", "'l'"]], ["call-function", "vowel_count", ["\"supercalifragilisticexpialidocious\""]], ["call-function", "vowel_count", ["\"facetious\""]], ["call-function", "vowel_count", ["\"phhhht\""]] ]
Forbidden substrings json list of strings e.g. `["for","while"]`	remove
Solution visibility	remove
Java imports json list of importables e.g. `["java.util.*"]`	remove
Override Java classname else defaults to websheet name	remove
Dependent on other websheets? json list of websheet names in this folder e.g. `["DataStructure"]`	remove
Is example? i.e., just a demo	remove
Add compiler flag(s) json list of flags e.g. `["-Wno-unused-variable"]`	remove
Remove default compiler flag(s) json list of flags see default_cppflags e.g. `["-Wno-write-strings"]`	remove

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