cpp/var-expr/char_arith Source

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Description
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It is important to remember that the computer treats <tt>char</tt> variables as numbers until 
we actually try to print them. In addition, it will convert <tt>char</tt> constants to 
their ASCII number. So writing <tt>'a'</tt> is the same as writing the number <tt>97</tt>.

Thus we can perform arithmetic on those numbers or use comparison operators!
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Copied from problem cpp/var-expr/hello (author: daveagp@gmail.com)

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

Correct answer
Template / Reference solution

Template / Reference solution

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

int main() {
// Make the words "true" and "false" print for Boolean expressions
cout << boolalpha;

char c = 97;
cout << "97 as a char is really " << c << endl;

// try to print out the letter 'b' by doing arithmetic
c = \[ c + 1 ]\;
cout << "This should print 'b' " << c << endl;

// Make the new value of 'c' equal the old value plus 25
c = 'a' + 25;

// *** Can you guess what character will print ****
cout << "Can you guess what will print...answer: " << c << endl;

// Make another char variable
char d = 'B';

// Let's try to check if the value of a char variable is between a-z
cout << (d >= 'a' && d <= 'z') << endl;

// One other difference is how digits are stored. There is
// a difference between 1 and '1'. 1 is the decimal number 1.
// '1' is the ASCII code (decimal 49) that causes '1' to display
// on the screen.
char e = \[ '1' ]\; // play with this value
cout << "Let's try to display the digit 1: " << e << endl;

// Let's try to print multiple digits. What's wrong with this?
\[
cout << "10" << endl;
\show:
cout << '10' << endl;
]\

return 0;
}

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Property	Value
Description html markup shown to student	It is important to remember that the computer treats <tt>char</tt> variables as numbers until <br> we actually try to print them. In addition, it will convert <tt>char</tt> constants to<br> their ASCII number. So writing <tt>'a'</tt> is the same as writing the number <tt>97</tt>. <p> <strong>Thus we can perform arithmetic on those numbers or use comparison operators!</strong>
Epilogue html markup shown when solved	remove
Public permissions	remove
Remarks Comments, history, license, etc.	Copied from problem cpp/var-expr/hello (author: daveagp@gmail.com) 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 <iomanip> using namespace std; int main() { // Make the words "true" and "false" print for Boolean expressions cout << boolalpha; char c = 97; cout << "97 as a char is really " << c << endl; // try to print out the letter 'b' by doing arithmetic c = \[ c + 1 ]\; cout << "This should print 'b' " << c << endl; // Make the new value of 'c' equal the old value plus 25 c = 'a' + 25; // * Can you guess what character will print ** cout << "Can you guess what will print...answer: " << c << endl; // Make another char variable char d = 'B'; // Let's try to check if the value of a char variable is between a-z cout << (d >= 'a' && d <= 'z') << endl; // One other difference is how digits are stored. There is // a difference between 1 and '1'. 1 is the decimal number 1. // '1' is the ASCII code (decimal 49) that causes '1' to display // on the screen. char e = \[ '1' ]\; // play with this value cout << "Let's try to display the digit 1: " << e << endl; // Let's try to print multiple digits. What's wrong with this? \[ cout << "10" << endl; \show: cout << '10' << endl; ]\ return 0; }
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
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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