Operator Example and Strings - Lecture Slides | CISC 181, Study notes of Computer Science

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operator example

and strings

last class

three ways to do it

some operators only work with some ways

parameters and return values - thinking about const and references

mixing types - adding Money and int

applying operators

how could we make it easier to work with the Store example?

overload << to make it easier to display

overload +=, -= for deposit/withdrawal

strings

a sequence of characters

two different kinds

C-style string (char arrays)

string class

character manipulation

has some handy tools:

int toupper(char)

int tolower(char)

bool isalpha(char)

and many more! (p. 380)

be very careful when using the ones that return ints!

C strings

an array of characters: char str[] = “Hi”;

in this case (no array size), it picks the size automatically

null terminator - the end of the string is a special character ‘\0’

as a numeric value, this is 0

C strings

significance of the null terminator

loops use it to process a string: int i = 0; while (str[i] != ‘\0’) cout << str[i] << “ “;

if the null terminator is overwritten somehow, it’ll just keep going through memory

C strings

= and == don’t work like normal

= just fails in normal settings, use strcpy(to, from) in cstring instead

strcpy(to, from, num_chars) is another form

== will just check that the array pointers are the same, which isn’t comparing contents

I/O with C strings

can use with cout (works normally)

can use with cin (gets one word)

if you want to get multiple words, use cin.getline(string, max_chars)

be careful about using both >> and getline in the same program!

I/O stuff

cin has some other handy functions:

cin.get() - gets a char

cin.peek() - looks at the next char but doesn’t change the buffer

cin.putback(char) - puts a char back

cin.ignore(int num_chars, char terminator) - ignores up to num_chars on the stream or until it hits the terminator char

next time

C++ string class

pointers overview

midterm review