CSC 107 – Programming For Science

Announcements  Memorization is not important, but…  … you will all still be responsible for information  Instead use your resources: notes, books, slides, etc.  Figured out problem using Eclipse in labs  Easy to work around problem via several options  Bringing thumbdrive easiest, but is not required  During the day, tutors available in WTC 206/208  Weekly assignment #2 posted to Angel

Variables, Constants, & More General CasesExamples Variable Declaration dataType name; dataType name = value; dataType name(value); dataType name, anotherName; dataType name = value, anotherName; int count; bool monkey = true; float avg(10.0); char help,letter; char a=‘a’,letter; Constant Declaration const dataType name = value; const double PI=3.1; Symbolic Constant #define NAME value #define AGE 34

Data Types  Each variable also has data type  How program treats variable’s value defined by this  Single true or false value held by bool  C/C++ defines 7 numeric data types  Integer types: short, int, long, long long  Decimal types: float, double, long double  char data type can hold a character

Data Types  Each numeric data type can be one of 2 types  Signed (both positive & negative) version is default  If data must be non-negative use unsigned _____  Upper range of variable is doubled  Warned when using signed & unsigned together  Only certain assignments allowed in system  Can assign an integer to a decimal variable  Error assigning decimal to integer variable, since its hard

Program Outline  Once upon a time…  … some stuff happens…  … and they all lived happily ever after

Program Outline  Once upon a time…  All programs must begin somewhere  Defines what is worked upon during rest of program  For non-trivial programs, requires receiving input  When starting program, first steps always same: 1. What is the input? 2. What will the input look like? 3. How will the data be entered?

Reading From The Keyboard  Easiest to get input from the keyboard  Reading from files possible; discussed later in term  C++ lacks standard, so writing GUI much harder  C++ defines cin to get user’s input  As easy to use as delivering food to Granny’s house  When cin hit, program waits until it has input  User must press enter for line to be able to be read  Editing not seen by program; only receives final line

Programming Using cin  Used to read one or more values at once: cin >> variable ; cin >> variable1 >> variable2 ;  Reads where last cin stopped reading input  Automatically skips past whitespace  Data type of variable determines what is read  Stops reading at first non-usable value in input  If input is not usable, will set variable equal to 0

cin Example >>

cin Example >>

cin Example >>

Program Outline  Once upon a time…  Get the input using cin from the keyboard  … some stuff happens…  … and they all lived happily ever after

Some Stuff Happens  This really depends on specific project details  Focus of most of term, we will skip this today

Program Outline  … and they all lived happily ever after  All good processing comes to end & report results  Shows program worked and provides feedback  Results takes many forms, focus on printing today  When starting program, second steps ask: 1. What must be output? 2. How can output be presented best? 3. Will it be pretty?

Using cout to Print  Already seen how to print text using cout cout << “Hello World” << endl;  Prints out whatever is placed between quotes  endl goes to next line and prints out immediately  Use escape sequences for fancier text output \n  newline (move to start of next line) \t  tab (go to next column that is multiple of 8) \\  \ (backslash character) \”  “ (quotation mark)

Can Print Out Multiple Items  cout can also print out value of variables int bob = 2; double j = 4.5; char var = ‘a’; cout << “Hello ”; cout << bob << endl; cout << j << endl; cout << var << endl; cout << j << “ is not ” << bob << endl; cout << bob << “ equals bob” << endl; cout << var << bob << j << endl;

But Can It Be Used?  cout built to provide basics needed to work  Prints out as many digits as needed  No extra spaces or tabs used  Scientific notation cannot be used  Often want to format results  Significant digits can matter  Tables make reading faster

Real World Strikes Again TrollPrincess

First Way To Format Output #include using namespace std; int main() { int k = 4; cout << k << endl; cout.width(4); cout << k << endl; cout << k << endl; cout.setf(ios::showpos); cout << k << endl; cout.width(3); cout.setf(ios::left); cout << k << k << endl; }

Second Way To Format Output #include #include using namespace std; int main() { int k = 4; cout << k << endl; cout << setw(4) << k << endl; cout << k << endl; cout.setf(ios::showpos); cout << k << endl; cout.setf(ios::left); cout << setw(3) << k << k << endl; }

Your Turn  Get in groups of 3 & work on following activity

For Next Lecture  Read sections 6.1 – 6.7 for Friday  How can we use the variables?  What operations exist for us to use?  What do we mean by order of operations?  Week #2 weekly assignment due Tuesday  Problems available on Angel  If problem takes more than 10 minutes, TALK TO ME!