String and Character Manipulation http://cs.mst.edu C-style Strings - - PowerPoint PPT Presentation

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String and Character Manipulation http://cs.mst.edu C-style Strings - - PowerPoint PPT Presentation

Jun 11, 2023 258 likes •858 views

String and Character Manipulation http://cs.mst.edu C-style Strings (ntcas) char name[10] = Clayton; C++ Standard Library Strings (a.k.a. Standard String Class) #include <string> using std::string; ... string name =

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http://cs.mst.edu

String and Character Manipulation

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http://cs.mst.edu

C-style Strings (ntcas)

char name[10] = “Clayton”; #include <string> using std::string; ... string name = “Clayton”;

C++ Standard Library Strings

(a.k.a. Standard String Class)

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std::string

#include <string> using std::string; int main() { string name = “Clayton”; cout << name.length();

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std::string input limitations

string name; cout << “What‟s your name? ”; cin >> name; cout << name << endl;

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std::string input limitations

string name; cout << “What‟s your name? ”; cin >> name; cout << name << endl;

User enters: Pattie Boyd

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std::string input limitations

string name; cout << “What‟s your name? ”; cin >> name; cout << name << endl;

System outputs: Pattie

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std::string input limitations

string name; string hometown; cout << “What‟s your name? ”; cin >> name; cout << “What is your hometown?”; cin >> hometown;

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std::string input limitations

string name; string hometown; cout << “What‟s your name? ”; cin >> name; cout << “What is your hometown?”; cin >> hometown;

System outputs: What’s your name?

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std::string input limitations

string name; string hometown; cout << “What‟s your name? ”; cin >> name; cout << “What is your hometown?”; cin >> hometown;

User enters: James Marshall

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std::string input limitations

string name; string hometown; cout << “What‟s your name? ”; cin >> name; cout << “What is your hometown?”; cin >> hometown;

System places “James Marshall” into the input buffer

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std::string input limitations

string name; string hometown; cout << “What‟s your name? ”; cin >> name; cout << “What is your hometown?”; cin >> hometown;

System pulls “James” from the buffer and into name

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std::string input limitations

string name; string hometown; cout << “What‟s your name? ”; cin >> name; cout << “What is your hometown?”; cin >> hometown;

System outputs: What is your hometown?

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std::string input limitations

string name; string hometown; cout << “What‟s your name? ”; cin >> name; cout << “What is your hometown?”; cin >> hometown;

System does not wait for the user input

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std::string input limitations

string name; string hometown; cout << “What‟s your name? ”; cin >> name; cout << “What is your hometown?”; cin >> hometown;

Instead “Marshall” is pulled from the buffer and into hometown

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

Delimiter Character is NOT included in input; it’s discarded.

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

System outputs: What’s your name?

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

User enters: Janis Joplin

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

System outputs: What is your hometown?

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

User enters: Port Arthur

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

System outputs: Janis Joplin

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std::string input fix

// getline(input_stream,string_var,delimiter_char); string name; string hometown; cout << “What‟s your name? ”; getline(cin, name, „\n‟); cout << “What is your hometown?”; getline(cin, hometown, „\n‟); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

System continues output: Janis JoplinPort Arthur

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std::string alternative fix

string name; string hometown; cout << “What‟s your name? ”; getline(cin, name); cout << “What is your hometown?”; getline(cin, hometown); cout << “Name: “ << name; cout << “Hometown: “ << hometown;

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std::string more input nuances

string name; int age; cout << “What‟s your age? ”; cin >> age; cout << “What‟s your name? ”; getline(cin, name);

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std::string more input nuances

string name; int age; cout << “What‟s your age? ”; cin >> age; cout << “What‟s your name? ”; getline(cin, name);

System outputs: What’s your age?

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std::string more input nuances

string name; int age; cout << “What‟s your age? ”; cin >> age; cout << “What‟s your name? ”; getline(cin, name);

User enters: 8

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std::string more input nuances

string name; int age; cout << “What‟s your age? ”; cin >> age; cout << “What‟s your name? ”; getline(cin, name);

System places “8\n” into the input buffer

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std::string more input nuances

string name; int age; cout << “What‟s your age? ”; cin >> age; cout << “What‟s your name? ”; getline(cin, name);

System pulls “8” from the buffer and into age

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std::string more input nuances

string name; int age; cout << “What‟s your age? ”; cin >> age; cout << “What‟s your name? ”; getline(cin, name);

System outputs: What’s your name?

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std::string more input nuances

string name; int age; cout << “What‟s your age? ”; cin >> age; cout << “What‟s your name? ”; getline(cin, name);

System does not wait for the user input

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std::string more input nuances

string name; int age; cout << “What‟s your age? ”; cin >> age; cout << “What‟s your name? ”; getline(cin, name);

Instead it pulls “\n” from the buffer into name and getline is finished

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std::string vs C-string(ntca)

string sname; const int SIZE = 80; char cname[SIZE]; cout << “What‟s your given name? ”; getline(cin, sname); cout << “What‟s your family name? ”; cin.getline(cname, SIZE-1); //different syntax!!

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more C-string getline

const int SIZE = 10; char name[SIZE]; cout << “What‟s your name? ”; cin.ignore(500, „\n‟); cin.getline(name, SIZE-1); cout << name << endl;

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more C-string getline

const int SIZE = 10; char name[SIZE]; cout << “What‟s your name? ”; cin.ignore(500, „\n‟); cin.getline(name, SIZE-1); cout << name << endl;

? ? ? ? ? ? ? ? ? ? [0] [1] [2] [3] [4] [5] [6] [7] [8] [9]

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more C-string getline

const int SIZE = 10; char name[SIZE]; cout << “What‟s your name? ”; cin.ignore(500, „\n‟); cin.getline(name, SIZE-1); cout << name << endl;

System outputs: What’s your name?

? ? ? ? ? ? ? ? ? ? [0] [1] [2] [3] [4] [5] [6] [7] [8] [9]

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more C-string getline

const int SIZE = 10; char name[SIZE]; cout << “What‟s your name? ”; cin.ignore(500, „\n‟); cin.getline(name, SIZE-1); cout << name << endl;

System clears any extraneous \n from the input buffer

? ? ? ? ? ? ? ? ? ? [0] [1] [2] [3] [4] [5] [6] [7] [8] [9]

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more C-string getline

const int SIZE = 10; char name[SIZE]; cout << “What‟s your name? ”; cin.ignore(500, „\n‟); cin.getline(name, SIZE-1); cout << name << endl;

User enters: Chimley

C h i m l e y \0 ? ? [0] [1] [2] [3] [4] [5] [6] [7] [8] [9]

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more C-string getline

const int SIZE = 10; char name[SIZE]; cout << “What‟s your name? ”; cin.ignore(500, „\n‟); cin.getline(name, SIZE-1); cout << name << endl;

System outputs: Chimley

C h i m l e y \0 ? ? [0] [1] [2] [3] [4] [5] [6] [7] [8] [9]

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Extraction vs. getline

  • The extraction operator (cin>>variable) will

always skip leading whitespace and leave \n in the buffer.

  • The getline functions will read leading

whitespace and will not leave the \n in the buffer. Rule: always know what is in your input buffer.

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#include<cctype>

  • toupper(char)
  • returns the uppercase of arg sent toupper('a'); -> 'A„
  • tolower(char)
  • similar
  • isupper(char)
  • returns bool: true if uppercase isupper('a'); -> false
  • islower(char)
  • similar
  • isalpha(char)
  • similar
  • isdigit(char)
  • similar
  • ispunct(char)
  • returns bool: true if punctuation ispunct('!'); -> true
  • isspace(char)
  • returns bool: true if whitespace – space, newline, tab
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C-string Manipulation

int i = 0, count = 0; char ntca[20] = “Hello! Hi.”; while (ntca[i] != „\0‟) { if (ispunct(ntca[i])) count++; i++; } cout<<count<<endl;

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C-string Manipulation

int i = 0, count = 0; char ntca[20] = “Hello! Hi.”; while (ntca[i] != „\0‟) { if (isspace(ntca[i])) count++; i++; } cout<<count<<endl;

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C-string Manipulation

int i = 0, count = 0; char ntca[20] = “Hello! Hi.”; while (ntca[i] != „\0‟) { ntca[i] = toupper(ntca[i]); i++; } cout<<ntca<<endl;

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HELLO! HI.

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Write Your Own

bool IsDigit (const char input)

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Write Your Own

bool IsDigit (const char input) { bool digit = false; if (input >= 48 && input <= 57) digit = true; return digit; }

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Write Your Own

bool IsDigit (const char input) { return(input>=48 && input<=57); }

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Character Input and Output

  • get – allows one character to be read from input
  • cin.get(char_variable);
  • peek – reads the next character from the input buffer

without extracting it

  • char_variable = cin.peek();
  • putback – places the character back into the input buffer
  • cin.putback(char_variable);
  • put – outputs a single character
  • cout.put(char_variable)
  • equivalent to cout << char_variable
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get

char next; cout<<”enter your poem: “; do { cin.get(next); cout<<next; } while (next != „\n‟);

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get

char next; cout<<”enter your poem: “; do { cin.get(next); cout<<next; } while (next != „\n‟); char poetry[500]; cout<<”enter your poem: “; cin.getline(poetry, 499); cout<<poetry;

getline vs.

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Input Options

  • getline()
  • reads line-by-line
  • cin >>
  • reads word-by-word
  • get()
  • reads character-by-character
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End of Session