Learning C from Java

These pages give information for Java programmers wishing to learn the C programming language. Mostly, though, programming in C requires no great paradigm shift from Java, since they are closely related. The most difficult changes are understanding pointers, and structuring large programs.

These pages are gratefully copied from and presented, with permission, from their author Steven Simpson.

Contents

• Java/C differences
• Speed of execution vs portability
• Speed of execution vs speed/ease of development
• Primitive types
• Comments
• Structures instead of classes
• Enumerations
• Unions
• Single namespace for functions and global variables
• Lack of function name overloading
• Type aliasing
• Declarations and definitions
  • Functions and their prototypes
  • Global objects
  • Local objects
  • Scope
• Empty parameter lists
• Program modularity
• Preprocessing
  • File inclusion
  • Macros
  • Conditional compilation
• Pointers instead of references
  • Pointer types
  • Null and undefined pointers
  • Dangling pointers
  • Passing arguments by reference
  • Pointers to structures and unions
  • Pointers to functions
  • Pointers to pointers
  • Generic pointers
• Arrays and pointer arithmetic
  • Initialising arrays
  • Array-pointer relationship
  • Passing arrays to functions
  • Array length
  • Arrays as function parameters
• const instead of final
  • Pointers to const objects
  • const pointers
• Characters and strings
• Dynamic memory management
• Lack of exceptions
• main() function
• Standard library facilities