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Need of constructor in c plus plus?
There is no specific keyword for a constructor in C++. Simply define and declare a method of the class with the same name as the class and it will be a constructor. A constructor with no arguments is the default constructor, a constructor with one argument of class type is the copy constructor, and a constructor with one argument of some other type is the conversion constructor. You can provide other overloaded constructors if you want.
How a string can be handled by array?
A string is an array. To be precise, a string is an array where every element is a character type. The term string simply relates to the fact the array (like any other type of array) resides in contiguous memory, thus forming a string of characters in memory.There are in fact two types of string array. The most common is the ASCII string, where each element is 1 byte in length (an array of type char). The other is the UNICODE string where each element is 2 bytes in length (an array of type wchar_t).In essence, ASCII strings are constructed from character codes 0-255 in the standard ASCII character set, while UNICODE can represent up to 65,536 different character codes, the first 256 being the same as the ASCII character set. UNICODE is generally used to provide character codes that are not available in ASCII, however many systems (Microsoft in particular) handle all strings as UNICODE strings (converting to and from ASCII as required). If you do a lot of string manipulation, then it is often best to use UNICODE at all times to reduce the amount of conversions going on in the background (check your compiler's documentation for specifics).When dealing with strings we often talk about string buffers. A buffer is simply an array of a specific size (allocated dynamically or statically) within which we can store a sequence of character codes. Since characters are consistently either one byte or two bytes long, it's easy to determine how many characters we can place in these buffers.However, just to confuse matters, there is actually a third type of string known as a variable-width encoded string. Microsoft calls these MBCS strings, but this really means multibyte character set, which is not the same. The width of a character is determined by the encoding, not the character set. The details don't really concern us, but suffice to say, each character has variable-width and there are many different encoding schemes available. As a general rule, if you must deal with variable-width encoded strings, use UNICODE instead, and only encode as variable width when you must. It'll make your life a lot simpler in the long run.You will undoubtedly encounter other types of string, such as std::string (and its UNICODE equivalent, std::wstring). This is really just an object that encapsulates a character array so you can use it just as you would a standard character array. However, do not let this fool you -- it is not a character array per se, it is merely a wrapper that mimics an array. There is an underlying array within the object's members, and several useful methods to manipulate the array (such as concatenating two strings), however memory management is handled by the object. While this simplifies things for programmers, it is not the most efficient way to store a string when that is all you want to do. But if you want to actually manipulate the string, then std:string is as good a way as any.To make use std:string you must include in your project. Do not confuse this with which merely declares a set of functions for manipulating c strings and arrays (the old fashioned way). This header is often called "cstring", which is often confused with the Microsoft-specific class CString (note the captialisation). CString can be likened to std:string in a lot of respects and crops up virtually everywhere in Microsoft objects. It is actually derived from the CStringT template which is itself derived from CSimpleStringT. It is therefore more complex, but the interface is extremely simple to use and if you do a lot of string manipulation, then CString can make life that much easier. But as it is not part of the standard language, its best avoided when code must be shared between platforms.
How do you write a program to find the length of a string?
/* with run-time library */ int len; char* str; len = strlen (str); /* without run-time library */ int mystrlen (const char* str) { int len; while (*str != '\0') { len++; str++; } return len; } int len; char* str; len = mystrlen(str);
How will you create a net component for displaying daily greeting message to remote system?
Private Sub Command1_Click() Dim objAdd As New clsAddPublic.display MsgBox(objAdd.display()) End Sub Namespace Tester Public Interface Tester Function GetTime() as Integer End Interface ClassInterface(ClassInterfaceType.None),_ProgId("Tester.Numbers")> Public class Tester Implements Tester Public Tester() Public Function GetTime() As integer Implements Tester.GetTime Dim Time As Integer Time = DateTime.Now If (Time<12) MessageBox("GOOD MORNING") Elseif (Time=12) Msgbox("GOOD AFTERNOON") ElseIf(Time>18) Msgbox("GOOD NIGHT") End If End If End If End Function Bool CNickDlg::OnInitDialog() CDialog::OnInitDialog(); CString strmessage; Tester::Time *com-ptr; CoInitialize(NULL); Tester::NumbersPtr p(Tester::Time); Com-ptr = t; Int t-Time = com_ptr -> GetTime(); SetIcon(m-hicon, TRUE); SetIcon(m-hicon, False); End Namespace
Write a function which takes your text as an input and print it in a center of the box in c plus plus?
C++ has no generic graphics capability whatsoever. Graphics are platform-specific, and every C++ implementation provides its own API and libraries specific to the intended platform. For instance, the following user-defined Visual C++ MFC function will centre any text (t) within a given rectangle (r) relative to the given device context (dc): void centre_text(CString& t, CRect& r, CDC& dc) { CRect b; // bounding rectangle. // Calculate the bounding rectangle of the text: dc.DrawText( t, b, DT_CALCRECT ); // Position the bounding rectangle in the centre of the given rectangle: b.MoveToXY( r.left + (( r.Width() - b.Width() ) / 2 ), r.top + (( r.Height() - b.Height() ) / 2 )); // Draw the text in the bounding rectangle: dc.DrawText( t, b, DT_NOCLIP ); } Note that the above code is non-generic and therefore cannot be ported to other platforms. It will only work in Visual C++ MFC applications. However, the principal will be largely the same on other platforms: calculate the bounding rectangle, move it to the centre of the intended rectangle and then print the text in the bounding rectangle.
Write a c program to accept alist of 10 namews input by user then display the sorted list of names back to the user?
, since you seem to be needing help with your homework, I can give you some psuedo code to help you on your way! [CODE] DECLARE ARRAY names[10] FOR i = 0 TO 9 names[i] = READ INPUT FROM USER ENDFOR CALL FUNCTION sort WITH PARAMETERS names, 10 [/CODE] In the event that you have to create your own sorting function, I can give you some pseudo-code for the selection sort - a relatively easy-to-write sorting algorithm which doesn't involve any complicated data structures, or more advanced programming patterns, such as recursion. [CODE] FUNCTION sort WITH PARAMETER ARRAY names[], size FOR i = 0 TO size min = i FOR j = i + 1 TO size //Find the smallest unsorted element in the list IF names[min] > names[j] THEN min = j END FOR SWAP names[i] AND names[min] END FOR END FUNCTION [/CODE] The above function sorts in ascending order. The smallest element will be located at names[0], and the largest will be at names[size]. If you are allowed to, you may be able to use C's builtin strcmp() function to compare strings (found in #include <string.h>, or #include <cstring> for a C++ compiler). PLEASE REMEMBER that you can not compare strings directly in C!!! A C-string is nothing more than a memory address. If you attempt to compare two strings directly, then the compiler will NOT compare the strings, but the memory addresses where the strings are located! If you can't use strcmp(), you will have to write your own string comparing function. When reading input from the user, you will need to use scanf() for C. Also remember that C does not do any memory management for you, so you need to make sure you have enough space in your character arrays to read in a string from the user. Because you have multiple names, you will need to create an array of arrays. Something similar to this: "char names[NUMBER_OF_NAMES][CHARACTERS_IN_A_NAME];" where NUMBER_OF_NAMES = 10 and CHARACTERS_IN_A_NAME is an arbitrary number, large enough to store a name (I would pick something like 100).
C program to implement transposition cipher using key?
/* * Transposition cipher cracker * * Algorithm used to find keys: * * n = keylength * t = textlength * a = t / n * b = t % n * d = accumulated rest terms * k = wanted plain text position * loc(k) = a * perm(k % n) + d(perm(k % n)) + k/n * * By Ben Ruijl, 2009 * * compile: g++ -O2 col.cpp */ #include <iostream> #include <cstring> #define MAXKEY 20 const char* buffer = "irtyhockeibtdaamoelatcnsronhoniirttcacdeiunsihaioarnndgpruphahirgtoarnmclspstwe"; int buflength; const char* crib = "computer"; int criblength; void print(int* perm, int n) { int a = buflength / n; int b = buflength % n; //invert perm int invperm[MAXKEY]; for (int i = 0; i < n; i++) invperm[perm[i]] = i; int d[MAXKEY] = {0}; for (int i = 1; i < n; i++) { d[i] = d[i -1]; if (invperm[i - 1] < b) d[i]++; } std::cout << "Found: "; for (int i = 0; i < buflength; i++) std::cout << buffer[a * perm[i % n] + d[perm[i % n]] + i / n]; std::cout << std::endl; } bool checkperm(int* perm, int n) { int cribpos = 0; int a = buflength / n; int b = buflength % n; //invert perm int invperm[MAXKEY]; for (int i = 0; i < n; i++) invperm[perm[i]] = i; int d[MAXKEY] = {0}; for (int i = 1; i < n; i++) { d[i] = d[i -1]; if (invperm[i - 1] < b) d[i]++; } for (int i = 0; i < buflength; i++) { if (buffer[a * perm[i % n] + d[perm[i % n]] + i / n] n - 1) checkperm(v, n); else { for (int i = start; i < n; i++) { int tmp = v[i]; v[i] = v[start]; v[start] = tmp; permute(v, start + 1, n); v[start] = v[i]; v[i] = tmp; } } } int main(int argv, char** argc) { int perm[MAXKEY]; for (int i = 0; i < MAXKEY; i++) perm[i] = i; buflength = strlen(buffer); criblength = strlen(crib); int curkey = 2; // start key while (curkey < MAXKEY) { std::cout << "Testing key " << curkey << std::endl; permute(perm, 0, curkey); // permutate keys curkey++; } return 0; }
What is a c plus plus program that accepts a mathematical expression from a user and converts it to postfix expression and evaluates the result?
#include <iostream> #include <cstdlib> #include <cstring> #include <cstdio> #define size 400 using namespace std; char infix[size]="\0",postfix[size]="\0",Stack[size]; int top; int precedence(char ch) { switch(ch) { case '^':return 5; case '/':return 4; case '*':return 4; case '+':return 3; case '-':return 3; default:return 0; } } char Pop() { char ret; if(top!=-1) { ret=Stack[top]; top--; return ret; } else return '#'; } char Topelem() { char ch; if(top!=-1) ch=Stack[top]; else ch='#'; return ch; } void Push(char ch) { if(top!=size-1) { top++; Stack[top]=ch; } } int braces(char* s) { int l,r; l=0;r=0; for(int i=0;s[i];i++) { if(s[i]=='(') l++; if(s[i]==')') r++; } if(l==r) return 0; else if(l<r) return 1; else return -1; } int main() { char ele,elem,st[2]; int T,prep,pre,popped,j=0,chk=0; cin>>T; while(T--) { j=0;chk=0;top=-1; strcpy(postfix," "); cin>>infix; chk=braces(infix); if(chk==0) { for(int i=0;infix[i];i++) { if(infix[i]=='(') { elem=infix[i]; Push(elem); } else if(infix[i]==')') { while((popped=Pop())!='(') { postfix[j++]=popped; } } else if(infix[i]=='^'infix[i]=='/'infix[i]=='*'infix[i]=='+'infix[i]=='-') { elem=infix[i]; pre=precedence(elem); ele=Topelem(); prep=precedence(ele); if(pre>prep) Push(elem); else { while(prep>=pre) { if(ele=='#') break; popped=Pop(); ele=Topelem(); postfix[j++]=popped; prep=precedence(ele); } Push(elem); } } else { postfix[j++]=infix[i]; } } while((popped=Pop())!='#') postfix[j++]=popped; postfix[j]='\0'; cout<<postfix; } } }
How can you pass variable arguments to a function in c?
## posted BY Pulkit ok. so to declare variable argements in arguments use this: ret_type function_name( . . .); using these three dots will tell compiler to include variable aarguments. Note: this feature has been included in New version of C,, this is not available in old compiler. thankx guys n grls ## posted BY Pulkit ok. so to declare variable argements in arguments use this: ret_type function_name( . . .); using these three dots will tell compiler to include variable aarguments. Note: this feature has been included in New version of C,, this is not available in old compiler. thankx guys n grls
