OOP2 Strings Flashcards
What type of data type is the string type?
Programmer defined type, not part of base C++
What library do you need to access std::string data type?
include <string></string>
What terminators do you need for strings?
“ … “
What are strings called with no characters?
Null/empty strings
What does length function do for std::string?
Returns unsigned int of how many chars are in string
What does size function do?
Returns unsigned int value of amount of chars in the string, same as .length() but works also with vector, arrays etc
What type is the unsigned int returned by length, size, etc?
std::string::size_type
What does .find() do?
Find returns an int of type string::size_type corresponding to the index of the string where the first char of the passed string was matched
What argument does .find() take?
It takes a substring to be found in the operated string
Find is case sensitive, true or false?
True
What happens if .find() finds no match?
Returns an named const of type string::npos
What happens if there are multiple identical subtrings for .find() to find?
Considers only the first
What does .substr() do?
Returns the piece of the string that starts at the specified index and continues for the number of chars specified
What arguments does .substr() take?
Substring takes two integers, first is starting index, second is length of sub string
Where does substring start counting from for length of returned string?
1 counted from same index as first argument
What does .at() function do?
Returns char at index of passed argument
What argument does .at() function take?
It takes an integer type and uses it as index value
How is string type different from char arrays / c strings in terms of
1. program runtime integrity,
2. in terms of how they are terminated?
- Strings have bound checking at compile time, arrays do not
- Strings are terminated with the enclosing speech marks, char arrays / c strings are terminated with the null character
What library is needed for toupper() and tolower()?
include <cctype></cctype>
What arguments do toupper() and tolower() take?
A single char data type
Other than .at(), how can you access chat at index?
std::string myString = “hello”;
ch = myString[4];
ch will contain ‘o’
How to concentrate strings?
+ operator or .append()
What does .compare() return?
0 if they are equal,
< 0 if the the passed string is shorter/first character doesn’t match
> 0 if the passed string is longer or first unmatching char is longer
What does .insert() take?
2 arguments: 1. Index, 2. String
How to obtain a cstring from a string?
myString.c_str();
How to clear a string and leave it empty/null?
myString.erase();
.replace takes?
Three arguments, first index where to start, second index where to end, third the string to replace with
.begin() and .end()?
Returns the index of the beginning and past-the-end characters of strings
.swap()?
Exchanges the content of two strings
.pop_back()?
Deletes last char of string
.push_back()?
Adds a new character at end of string, takes a single character as argument
Difference between [] and .at()?
[] does not bound check but does not throw an error,
.at() bounds checks
Erase takes two optional arguments. What is it?
Int for index from which to erase, and int for length for how long to erase
