DepartmentofComputerandInformationScience,Schoolof.pptVIP

Try Your First C Program #include stdio.h /* I/O header file */ main() { printf(“Hello world ”); printf(“Welcome to CSCI230\n“); printf(“I am John Smith\n”); } A C program contains one or more functions main() is the function name of your main (root) program { }: braces (left right) to construct a block containing the statements of a function Every statement must end with a ; \ is called an escape character \n is an example of an escape sequence which indicates newline Other escape sequences are: \t \r \a \\ \” Exercise: Use any editor to type and then save your first program as main.c % gcc main.c % a.out and observe its result. Identifiers Variable identifiers Begin with a letter or underscore: A-Z, a-z, _ The rest of the name can be letters, underscore, or digits Only the first 8 characters are significant on most compilers (those come after the 8th character will be ignored) while most of C compiler allows 32 significant characters. Example: _abc ABC Time time _a1 abcdefgh abcdefghi (may be the same as abcdefgh) Case sensitive Keywords: reserved names auto double if static break else int struct case entry long switch char extern register typedef float return union do go sizeof continue … Fundamental Data Type Four Data Types (assume 2’s complement, byte machine) Variable Declarations type v1,v2,v3, …, vn Example: int i; int j; float k; char c; short int x; long int y; unsigned int z; int a1, a2, a3, a4, a5; Numeric, Char, String Literals Literal Numeric literal fixed-point octal O32 (= 24D) hexadecimal OxFE or Oxfe (=254D) decimal int 32 long (explicit) 32L or 32l an ordinary integer literal that is too long to fit in an int is also to be long floating-point No single precision is used; always use double for literal Example: 1.23 123.456e-7 0.12E Numeric, Char, String Literals Character literal American Standard Code for Information Interchange (ASCII) Printable: single space 32 ‘0’ - ‘9’ 48 - 57 ‘A