C programming

• There is a small, fixed number of keywords, including a full set of flow of control primitives: for, if/else, while, switch, and do/while. There is one user-defined names are not distinguished from keywords by any kind of sigil.
• There are a large number of arithmetical and logical operators, such as +, +=, ++, &, ~, etc.
• More than one assignments may be performed in a single statement.
• Function return values can be ignored when not needed.
• Typing is static but weakely enforced all data has a type, but implicit conversions can be performed; for instance, characters can be used as integers.
• Diclearation syntax mimics usage context. C has no “define” keyword; instead, a statement beginning with the name of a type is taken as a declaration. There is no “function” keyword; instead, a function is indicated by the parentheses of an argument list.
• User-defined (typedef) and compound types are possible.
  • Heterogeneous aggregate data types (struct) allow related data elements to be accessed and assigned as a unit.
  • Array indexing is a secondary notion, defined in terms of pointer arithmetic. Unlike structs, arrays are not first-class objects; they cannot be assigned or compared using single built-in operators. There is no “array” keyword, in use or definition; instead, square brackets indicate arrays syntactically, e.g. month[11].
  • Enumerated types are possible with the enum keyword. They are not tagged, and are freely interconvertible with integers.
  • Strings are not a separate data type, but are conventionally implemented as null-terminated arrays of characters.
• Low-level access to computer memory is possible by converting machine addresses to typed pointers.
• Procedurea (subroutines not returning values) are a special case of function, with an untyped return type void.
• Functions may not be defined within the lexical scope of other functions.
• Function and data pointers permit ad hoc run time polymorphism.
  
• A preprocessor performs macro definition, source code file inclusion, and conditional compilelation.
• There is a basic form of modularity: files can be compiled separately and linked together, with control over which functions and data objects are visible to other files via static and extern attributes.
• Complex functionality such as i/o string manipulation, and mathematical functions are consistently delegated to library routines.