Trying to cram as much "knowledge" of C as possible on one page. Clearly this will be the Reminder... and not the Beginner... page.

The book I'm working from (for the moment) is Red Hat Linux 6 Unleashed; David Pitts, Bill Ball, et. al.; Sams; 1st Printing, 1999; ISBN 0-672-31689-7.

See:

• C Programming Language
• Cpl Hello World
• AboutThesePages

Contents

Introduction

• "Third-generation procedural describes computer languages that clearly distinguish the data used in a program from the actions performed on that data." First time I encountered that definition -- could be useful.
• The "unit" of a C program is the function -- every program must have main()
  • Declare: int swapadmin( int *, int *);
  • Define: int swapadmin( int *a, int *b);
  • Call: lower = swapadmin(&i, &j);
• Two kinds of data manipulated in C programs:
  • literals
  • variables -- must be declared before use -- int i;
• Basic data types:
  • integers
  • floating-point (real) numbers
  • characters
  • arrays (no string -- use an array of characters
• No boolean true / false, but in conditional expressions, 0 is false, nonzero is true
• Pointers (pointers, and dereferencing, and .. oh no!) -- wordsmith these descriptions until they really mean something to me, and are easily interpreted
  • & = dereference -- deal with the address of the data
  • * = treat as a pointer -- deal with the value pointed at

Here's a little test program that seems worthy of understanding:

main()
{
int i;
int *ptr;

i=5;
ptr = &i;
printf("%d %x %d\n", i, ptr, *ptr);
}

• Complex data structures (structs) struct typevar {type var1; type var2; type var3; ...}; followed by struct typevar structvar;
• Statements -- separated by semicolons
• Blocks -- statements surrounded by curly braces
• Expressions -- methods for combining values into new values
  • comparison -- see lists below
  • mathematical -- see lists below
  • bitwise -- see lists below
• Loop Control Statements (one line versions, for now)
  • while (expression) statement
  • do statement while (expression);
  • for(expr1;expr2;expr3) statement, which can also be done by a while statement: expr1; while (expr2) {statement; expr3}
• Interrupting a loop:
  • break -- terminates execution and exits loop
  • continue -- terminates execution and continues loop with next item
  • goto --
• Conditional Statements
  • if (expr) statement
  • if (expr) statement else statement
  • switch / case -- get an example -- trying: =switch {expr} case val1: statement; case val2: statement; default statement;
  • "ternary" if (??) -- ((expr) ? val1 : val2)
• Macros (the third part of (pointers, and dereferencing, and macros, oh no!) — some examples:

Comparison Operators

• < -- less than
• > -- greater than
• == -- equal
• <= -- less than or equal
• >= -- greater than or equal
• || -- logical or
• && -- logical and
• ! -- logical not

Mathematical Operators

Binary

• + -- add
• - -- subtract
• * -- multiply
• / -- divide
• % -- integer remainder (modulo??)

Unary

• - -- negate (??) (oops, I added this, assumed it existed -- it might not)
• ++ -- increment (x = x + 1)
• -- -- decrement (x = x - 1)

Bitwise Operators

• & -- bitwise AND
• | -- bitwise OR
• - -- negation (one's complement)
• << -- bit shift left
• >> -- bit shift right

Printing

printf(["<format_string>",] <comma_delimited_arguments>);

Format string options:

• %% -- percent sign
• %E, %e -- double in scientific notation
• %f -- double with decimal point
• %G, %g -- double -- format depends on value ?? (test)
• %X, %x -- hexadecimal with [capital, lowercase] letters
• %c -- single character
• %d, %i -- integer
• %ld -- long integer
• %n -- "count of charaters written in current printf"
• %o -- octal
• %p -- pointer (address or data??))
• %s -- "character pointer (string)"
• %u -- unsigned integer

Escape characters for strings:

• \"
• \'
• \?
• \ * \a -- (audible) bell
• \b -- backspace
• \f -- form feed (new page)
• \n -- newline
• \ooo -- octal number
• \r -- carriage return
• \t -- horizontal tab
• \v -- vertical tab
• \xhh -- hexadecimal number

Contributors

• () RandyKramer - 03 Apr 2003
• <If you edit this page: add your name here; move this to the next line; and include your comment marker (initials), if you have created one, in parenthesis before your WikiName.>

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