C++ Part 37

I/O Stream Example :

//Reads three numbers from the file infile.txt, sums the numbers,
//and writes the sum to the file outfile.txt.
#include <fstream>
using std::ifstream;
using std::ofstream;
using std::endl;
int main( )
{
ifstream inStream;
ofstream outStream;
inStream.open("infile.txt");
outStream.open("outfile.txt");
int first, second, third;
inStream >> first >> second >> third;
outStream << "The sum of the first 3\n"
<< "numbers in infile.txt\n"
<< "is " << (first + second + third)
<< endl;
inStream.close( );
outStream.close( );
return 0;
}

C++ Part 30

String | Getline and Cin

string s1, s2;
cin >> s1;
cin >> s2;
If the user types in
I love NavidPlus website.
s1 will receive value "I" and s2 will receive the value "love".
If you want your program to read an entire line of input into a variable of type string , you can use the function getline.
Example:
string line;
cout << "Enter a line of input:\n"; getline(cin, line); cout << line << "END OF OUTPUT\n";

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I/O with string Objects
You can use the insertion operator << with cout to output string objects. You can input a string with the extraction operator >> and cin.

When using >> for input, the code reads in a string delimited with whitespace.
You can use the function getline to input an entire line of text into a string object.
EXAMPLES
string greeting("Hello"), response, nextLine;
cout << greeting; cin >> response;
getline(cin, nextLine);

Intro to C++ Part 4

• Declaration of variables: How does the variable map onto memory? Updating variable: How do we update the variable, and what do we update it with? 
• I/O: How do we input and output data into the system? 
• Control: How do we control which statement gets executed next? 
• Modularity and Object Orientation: How do we organize the program to enable proper software engineering practices? 
• Comments: Used to describe code; ignored by compiler, but code unmaintainable without good comments! C/C++: on line beginning with // or surrounded by /*, */