CSC 107 – Programming For Science

History of C  Dennis Ritchie developed C from 1969 – 1973  While at Bell Labs, created language to develop Unix  Based upon B, an earlier programming language (Also used other, less funny, languages)

History of C  Popular since 1978 book by Kernighan & Ritchie  Language grown organically since its creation  Companies often add own features beyond standards

History of C++  Created by Bjarne Stroustrup to add objects to C  Immediately added other features to improve C  In 1983, renamed as C++ to show all the changes  Name is an inside joke: "++" is increment operator  Book published soon after in '85  Updated for quick growth  2.0 release in 1989  1998 adopted as ISO standard  C x in development now

C Versus C++ C++ is designed to be as compatible with C as possible, thereby providing a smooth transition from C

C Versus C++ C++ C

C Versus C++ C

 Latest standard of C added most C++ features  But classes & objects still not part of C language  For this reason, also not a part of CSC 107  C++ compiles almost all C programs natively  Differences are minimal and easily avoided  C++ is “looser C” once objects are removed  Several annoying restrictions removed from C  Often supported in C anyway, since make life easier

 Computers have no common-sense do what you tell them to do  They will only do what you tell them to do  NOT what you want them to do  NOT what you want them to do, which often differs

Case-Sensitivity  Example of computers being very literal  And language not helping by fixing what you say  main, Main, & MAiN treated as different words  Case of the letters matters, not just the words  Could be different, so C++ won’t change Main to main  Can help prevent easy mistakes from swapping names  With just a little practice, becomes second nature

“Whitespace”  One (very small) way C++ actually helps you  C++ treats whitespace equally – spaces, enters, & tabs  Does not matter if there is none, 1, or  Whitespace cannot be within a symbol  “ : : ” and “ :: ” are treated differently  One or more blanks between words needed  Wecansplitwordsbutthecomputercannot

“Whitespace”  One (very small) way C++ actually helps you  C++ treats whitespace equally – spaces, enters, & tabs  Does not matter if there is none, 1, or  Whitespace cannot be within a symbol  “ : : ” and “ :: ” are treated differently  One or more blanks between words needed  Wecansplitwordsbutthecomputercannot

Your First C++ Program #include using std::cout; int main() { /* Hi, Mom. This is a comment that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }

#include Statements #include using std::cout; /* Hi, Mom. This is a comment that goes over 2 line. */ int main() { std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }  Nearly every C++ file begins with this directive  May add more #include to include other files  Contents of included file usable as if it were here  Easy way to copy ideas across multiple files  Programs can use two types of #include statements  Include system file using #include  #include “ filename ” includes a file you wrote

Watch Me Pull a Rabbit #include using std::cout; /* Hi, Mom. This is a comment that goes over 2 line. */ int main() { std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }  For now, automatically start each file with this line  Details are unimportant – consider it magic

Watch Me Pull a Rabbit #include using std::cout; /* Hi, Mom. This is a comment that goes over 2 line. */ int main() { std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }  For now, automatically start each file with this line  Details are unimportant – consider it magic

Your First C++ Program #include using std::cout; int main() { /* Hi, Mom. This is a comment that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }

Using Commands #include using std::cout; /* Hi, Mom. This is a comment that goes over 2 line. */ int main() { std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }  More “magic”, but using has less important purpose  Tells compiler to make shortcut & save some typing  Two types of using statements to choose from  Specify single shortcut with using std::cout  using std; gives you a list of shortcuts to use  Unlike #include statements, using never required  Do not worry about it – will not be using them

Your First C++ Program #include using std::cout; int main() { /* Hi, Mom. This is a comment that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }

main Function #include using std::cout; int main() { /* Hi, Mom. This is a comment that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }  All C++ programs contain function called main  Tells computer where to start running program  Code inside the braces will be what is executed  For the moment, consider this more “magic”

main Function #include using std::cout; int main() { /* Hi, Mom. This is a comment that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end }  All C++ programs contain function called main  Tells computer where to start running program  Code inside the braces will be what is executed  For the moment, consider this more “magic”

Comments  Vital  Vital for writing and maintaining any program  Not required to run program - only for human eyes  Computer simply ignores anything in a comment  Use to describe code in simple English  Sie konnen auch auf Deutsch screiben  o U c%d wrte n txt msg  Should be used liberally  I add comments where cannot see what code does  Impossible to have too many comments, if readable

Comments in C++  Double slash comments continue to line’s end a = a – 4; // Hi, Mom! // This entire line is a comment!  /* … */ comments can be on one or more lines a = a - /* Hi, Mom! */ 4; /* This comment takes an entire line. */ /* This is a really long comment that * goes on to multiple lines. The stars on * lines 2 and on are optional, but * makes things easier to read. */

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

For Next Lecture  Read sections 4.1 – 4.10 in book for Monday  What is a data type?  What are variables?  How can we use variables in a program?  How are literal, constant, & variable different?  Week #1 weekly assignment due Tuesday  Problems available on Angel – covered 1 st two already  If problem takes more than 10 minutes, TALK TO ME!