Data Types

• Storage Size • Domain of all possible values • Operations

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C++ Data Types• char • int (short, long)• float (double) • string (C++ string)• bool• Array• C string (array of char as string)• Enumeration type• Structure• (typedef)• (ClassClass)• . . . 2

Storage Size• System dependent• char: 1 byte • int: 2 bytes• float: 4 bytes • bool: 1 or 2 bytes• C++ string: Reference (num of chars + 1)• Array: max number of elements type of elements• C string (array of char as string) max num of chars + 1• Structure Sum of all member fields

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Domain of Possible Values• char ASCII code table• int -32768 -- 32767• float Much larger range• string (both C string and C++ string) Any thing within “a string”• Array All elements are of the same type char, int, float, string, bool, structure…• Struct

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C++ Operations

• Input• Output• Assignment• Comparison• Arithmetic operations• Function return value• Function parameter• Others?

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Operations on intint x, y;

// Inputcin >> x;inFile >> x;

// Outputcout << x;outFile << x;cout << setw(9) << x << endl;

// Assignmentx = 10;y = x;

// Comparisonif (x <= y) cout << “x is no more than y.”;if (x == y) cout << “x is the same as y.”;// Syntax and Style

// Arithmetic operationsx += y;y = x % 5;

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Operations on int

// Function return valueint ReturnInt();

// Function parameters// Params: (in, out, inout)void IntParameters(int IntIn, int& IntOut, int& IntInOut);

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Operations on charchar x, y;

// Inputcin >> x; // skip white spacescin.get(x); // read in white spacesinFile.get(x);

// Outputcout << x;cout << setw(9) << x << endl;

// Assignmentx = ‘0’; // not null charx = ‘\0’; // null chary = x;

// Comparison: ASCII code valueif (x <= y) cout << “x is no more than y.”;if (x == ‘A’) cout << “x is a ‘A’.”;

// Arithmetic operationsx ++;y = x % 5;

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Operations on char

// Function return valuechar ReturnChar();

// Function parameters// Params: (in, out, inout)void charParameters(char charIn, char& charOut, char &charInOut);

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Operations on float

Same as int, except %

float x, y;

// Input// Output// Assignment// Comparison// Arithmetic operationsy = x % 5; // NO!// Function return value// Function parameters// Params: (in, out, inout)

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Operations on string(C++ string)

string x, y;

// Inputcin >> x;inFile >> x;

// Outputcout << x;cout << setw(9) << x;

// Assignmentx = “My String.”;y = x;

// Comparisonif (x > “CS1430”) cout << “x is larger than CS1430.”;if (x > “CS1430”) cout << "x is larger than " << char(34) << "CS1430" << char(34);if (x == y) cout << “x is the same as y.”;

// Arithmetic operations// NO!

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Operations on string (C++ string)

// Function return valuestring ReturnString();

// Function parameters// Params: (in, out, inout)void stringParameters(string stringIn, string& stringOut, string& stringInOut);

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Operations on Array

const int MAX_SIZE = 100;int size = 100;

int GoodIntArray[MAX_SIZE * 2 - 100];int badIntArray[size];float floatArray[100];string stringArray[MAX_SIZE];char charArray[MAX_SIZE];// Array of char or C StringStudentType CS143[25];

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Operations on Arrayint GoodIntArray[MAX_SIZE * 2 - 100];float floatArray[100];char charArray[MAX_SIZE + 1];

// Inputcin >> GoodIntArray;// NO!

cin >> floatArray;// NO!

cin >> charArray;// Yes! Treated as a String (null char inserted)

cout << GoodIntArray;// NO!

cout << floatArray;// NO!

cout << charArray;// Yes if treated as a string (must be null terminated)

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Operations on Array

int GoodIntArray[100];float floatArray[100];char charArray[101];

int A[100];A = GoodIntArray;// NO!

float B[100];B = floatArray;// NO!

char C[101];C = charArray;// NO!

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Operations on Array// Comparison

int A[100];if (A == GoodIntArray) cout << “Same array!”;// NO!

float B[100];if (B <= floatArray) cout << “B is smaller than floatArray.”;// NO!

char C[101];if (C > charArray) cout << “C is larger than charArray.”;// NO!

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Operations on Array

// Function return valueint A[] CannotReturnArray();// NO!

// Function parameters// Params: (in, out, inout, in)void arrayParameters(const int arrayIn[], float arrayOut[], char arrayInOut[], int size);

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C String (Array of Char)

• Using C++ string #include <string>• Using C string #include <cstring> Functions: strlen() strcpy() strcmp()

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Operations on C-String#include <cstring>

char Name[21]; // up to 20 chars, ending with ‘\0’

cin >> Name;// Yes, ‘\0’ is inserted

cout << name;// Yes, stop at ‘\0’

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Operations on C-StringName = “CS2430”;// NO!

strcpy(Name, “CS2430”);

if (Name > “CS1430”) cout << “Larger than 1430”;// NO!

if (strcmp(Name, “CS1430”) > 0) cout << “Larger than 1430”;

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Array of char vs. C-String

const int NUM_QUESTIONS = 50;const int NAME_SIZE = 20;

char quizName[NAME_SIZE + 1];char quizAnswer[NUM_QUESTIONS];

cin >> quizName;// C String!// ‘\0’ at the end

for (int i = 0; i < NUM_QUESTIONS; i ++) cin >> quizAnswer[i];// Not C String!// Not ending with ‘\0’

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Operations on structStudentType s1, s2;

// Inputcin >> s1;// NO!

cin >> s1.gpa;// YES!

// Outputcout << s1;// NO!

cout << s1.gpa;// YES!

s2 = s1;// Yes!

if (s1 < s2) cout << “s1 is smaller.”;// NO!

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Function Parameters

InThe function uses the value of the actual parameter.

OutThe function updates the value of the actual parameter and

passes it back to the calling function.(a function can only return one value using the return

statement)

InOutBoth In and Out

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Passing Function Parameters• Passing basic data types (int, float, char, string, bool) IN: Pass by value (without &) OUT, INOUT: Pass by reference (with &)• Passing arrays (including C-String) Always pass by reference (NO &) IN: const (No &)• Passing structs (Our programming rule) Always pass by reference with & IN: const (with &)• Passing structs (C ++ rule) IN: Pass by value (without &) OUT, INOUT: Pass by reference (with &)

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Test 3

• Wednesday• 60 points• File I/O• Enumeration• C-String• Selection Sort• Structure• Dynamic List• Deleting

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