The code reads in a number and then writes the result

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Unformatted text preview: 7. #include <iostream> using namespace std; int main ( ) { double x, y; cin >> x; y = x * 7; cout << y; return 0; } The first line of the body #include <iostream> declares two containers to hold using namespace std; numbers. The identifiers of these int main ( ) containers will be x and y. { It is important to declare every double x, y; cin >> x; identifier before it is used. y = x * 7; cout << y; return 0; Reading A C++ Program: Declaration } Simple declarations are of the #include <iostream> form: using namespace std; simple_type identifiers; int main ( ) { In this case the identifiers x double x, y; and y are declared to be of the cin >> x; type double. y = x * 7; For now we will consider two cout << y; simple types: double and int. return 0; } Reading A C++ Program: Declaration Reading A C++ Program: Declaration #include <iostream> A double is a number with a using namespace std; fractional part that can take on a very large range of magnitudes. An int is an integer number between about 2 billion to 2 billion. Always choose the one closest to your meaning. int main ( ) { double x, y; cin >> x; y = x * 7; cout << y; return 0; } Reading A C++ Program: Expressions The next 3 lines of the program are expressions. Expressions change and exchange data. The basic form of an expression is: expression; #include <iostream> using namespace std; int main ( ) { double x, y; cin >> x; y = x * 7; cout << y; return 0; } Reading A C++ Program: Expressions The first expression, cin >> x; will obtain input from the caller. int main ( ) The second expression, y { double x, y; = x * 7; multiples x by 7 cin >> x; and assigns the result to y. y = x * 7; The third expression, cout cout << y; << y; will output y to the return 0; caller. } #include <iostream> using namespace std; Reading A C++ Program: Semicolons int main ( ) { Denote the end of a double x, y; declaration or expression. cin >> x; Critical for determining y = x * 7; order of execution. cout << y; return 0; The most common errors are } omitted semicolons. ; #include <iostream> using namespace std; Next Lecture C++ Basics fun!...
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This note was uploaded on 03/27/2008 for the course ENGR 101 taught by Professor Ringenberg during the Fall '07 term at University of Michigan.

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