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C++:Working With Files -1

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A program typically involves either or both of the following kind of data communication:-1. Data transfer between console unit and program2. Data transfer between program and disk file.Input Stream- supplies data to program or reads data from file.Output Stream- recieves data from program or writes data to file.Input operation involves the creation of an input stream and linking it with the program and input file.
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Classes for FIle Stream OperationsI/O system of c++ contains a set of classes that defines the file handling methods.These include ifstream, ofstreamand fstream. These classes are derived from fstreambase class and corresponding iostreamclass.
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Opening and Closing of FileThe filename is a string of character conatining two parts - primary name and optional period with extension.
eg.  Input.data
        test.docOpening file using constructorThis method is useful when we use only one file in the st…

C++: Program for calculator using functions

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#include<iostream>
using namespace std; float sum(float, float);
float sub(float, float);
float mul(float, float);
float div(float, float); int main()
{
float x, y, res;
char choice;
cout << "Calculator\n\n";
cout << "Enter two numbers\n";
cin >> x >> y;
cout <<
"Operations \n '+' for addition \n '-' for substraction \n '*' for multiplication \n '/' for division \n";
cin >> choice;
switch (choice)
{
case '+':
res = sum(x, y);
cout << "Sum is :" << res;
break;
case '-':
res = sub(x, y);
cout << "Substraction is:" << res;
break;
case '*':
res = mul(x, y);
cout << "Multiplication is:" << res;
break;
case '/':
res = div(x, y);
cout << "Division is :" << res;
break;
default:
cout << "Enter correct choice";
break;
}
return 0;
} float sum(float a, float b)
{

C++: I/O Operations -2

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Formatted Console I/O OperationsTo access manipulators the file iomanipshould be included in program.cout.width(w);to define width of a field necessary for output of item.
w is field width(no. of columns)cout.precision(d)to specify no. of digits to be displayed after the decimal point.By default, floating no. are printed with six digits after the decimal point.  cout.precision(3);
  cout<<3.15159<<"\n";
  cout<<2.50032<<"\n";3.142(rounded to nearest cent)
2.5 (no trailing zeros)Unlike width(), precision() retains the setting in effect until it is reset.cout.fill(ch);  to fill unused position by any desired character.By default, the unused positions of the field are filled with the white spaces.  cout.fill("*");
  cout.width(10);
  cout<<5250<<"\n";******5250fill() also stays in effect till we change it. cout.setf(arg1,arg2); 
arg1 is one of the formatting flags specifies the format action required for outp…

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