Fun to Program – C Language

Date: 2013/08/28 (initial publish), 2021/08/02 (last update)

Source: en/

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This was originally written and created around 2013 and may require to be updated. (2021)

C Language

Except for some functional languages such as Scheme, many procedual languages share quite a bit of similarities. C language is a good start in terms of its gramatical simplicity.

Program control sequence keywords

C syntax meaning
expression; simple expression statement
{statement...} block statement
if (expression) statement conditional execution
if (expression) statement else statement conditional executions
switch (expression) {case const-express: {statement... break;}... default: statement} conditional branch execution
while (expression) statement conditional loop execution
do statement while (expression); conditional loop execution
for (i = 0; i++; i < n) statement conditional loop execution i = 0, 1, 2, …, n-1
return expression; return by exiting function
continue; continue to the next loop execution
break; break out of the loop/switch execution
goto identifier goto identifier label in the current function

Type, structure, union, storage class declarations

C declaration meaning
void pointer type
char byte type
int integer type
float single-precision floating point type
double double-precision floating point type
enum enumeration constant type
short type qualifier
long type qualifier
signed type qualifier
unsigned type qualifier
const type qualifier
volatile type qualifier
union union declaration
struct structure declaration
auto storage class
register storage class
static storage class
extern storage class
typedef storage class

Unary operators

C operator meaning
- arith. minus
~ bitwise not
++ increment.
-- decrement.
sizeof object size
(typename) type conversion
* reference (pointer, indirection)
& dereference (pointer, address of)

Binary operators

C operator meaning
+ arith. addition
- arith. substraction
* arith. multiplication
/ arith. division
% arith. modulo
& bitwise and
| bitwise or
^ bitwise xor
<< bitwise shiftL
>> bitwise shiftR
== equal. test.
!= non-equal. test.
< less than
<= less or equal.
> more than
>= more or equal.
! bool. not
&& bool. and
|| bool. or
= assign.
+= aug. assign. with arith. addition
-= aug. assign. with arith. substraction
*= aug. assign. with arith. multiplication
/= aug. assign. with arith. division
%= aug. assign. with arith. modulo
&= aug. assign. with bitwise and
|= aug. assign. with bitwise or
^= aug. assign. with bitwise xor
<<= aug. assign. with bitwise shiftL
>>= aug. assign. with bitwise shiftR
. member select. (structure)
-> member select. (structure, pointed by parent)
, sequencing

Ternary and other operators

C operator meaning
? : cond. eval.
() subexpression grouping
() calling function argument
[] array subscript

Despite its simplicity, writing good code under C is not easy. If you write C code carelessly with fixed width character array buffers, you are sure to hit a buffer overflow bug which is serious bug. Memory management to cope with variable length character array buffers under C is non-trivial task.

Operator Precedence

operator type operator expression precidence space
func. operator, array operator, structure member operator func(...) array[...] parentptr->id L <- R no
prefix unary operator (address-of, pointer-to, plus, minus, bitwise not, logical not) & * + - ~ ! L <- R no (yes before)
binary operator (mul., div., mod.) * / % L -> R yes
binary operator (add, sub) + - L -> R yes
bitwise shift operator (shr, shl) >> << L -> R yes
logical relational operator (gt,lt,ge,le) > < >= <= L -> R yes
logical equity operator (eq,ne) == != L -> R yes
bitwise and operator (and) & L -> R yes
bitwise xor operator (xor) ^ L -> R yes
bitwise or operator (or) | L -> R yes
logical and operator (and) && L -> R yes
logical or operator (or) || L -> R yes
conditional operator ? : L <- R yes
assignment operator = *= /= %= += -= <<= >>= &= ^= |= L <- R yes
comma operator , L -> R no (yes for after)

Please note:

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