C Commands (: Fortran Commands)

/* ..... comments ...... */

Preprocessors

#include filename : #include < stdio.h>, #include "mylib.h"

#define name[(parameters)] value-expression : PRAMETER

#undef name

if condition

..... statement ..... ;

#elif condition

..... statement ..... ;

#else

..... statement ..... ;

#endif

#ifdef name : if name is defined

..... statement ..... ;

#ifndef name : if name is not defined

..... statement ..... ;

Declaration of subroutine-function name (except int or void type)

type sub1 (par1, par2)

type sub2 (par.......)

type sub3 (par.......)

Declaration of Grobal variables : COMMON Block

Integer : short, int, long, unsigned short, unsigned, unsigned long

Real : float, double, long double

Character : char, unsigned char, signed char

Enumerated : enum

enum tagname {elemnt1, elemnt2, ....., elemntn} variablelist

Pointer : * &

*p : p is pointer variable (value stored in address p)

&var : pointer (address) of var

Character string name or Array name is a pointer : do not use &

Structured : struct strctname {item1; item2; ..... itemn;} strctdatalist

struct student {long st_id; char age; float GPA;} x, classa[30];

x.st_id, x.age, classa[1].GPA

struct bitstrct {bitfield1 : bitlnth1; ..... bitfieldn : bitlnthn} : bitwise structure

Shared : union : EQUIVALENCE

union [unioname] {char c; int i; float f;} a;

a.c, a.i, a.f

typeless : void

type array[n1][n2]....[nn]; : a[0][0]. a[0][1], a[0][2], ....., a[0][n2-1], a[1][0], a[1][1], a[1][2], ....., a[1][n2-1], a[2][0], .....

main() or subname(para.....)

Routine Variables;

{ Block Variables; ..... }

Arithmatic Operators : (+ -) (* / %(MOD))

Relational Operators : (< <= > >=) (== !=)

Logical Operators : &&(and) ||(or) !(not)

Bitwise Operators : ~(bitwise complement) &(bitwise AND) |(bitwise or) ^(bitwise XOR) <<(shift left) >>(shift right)

(aa<>n; : shift aa by n bits)

= += -= *= /= %= <<= >>= &= ^= |=

(a operator= c : a = a operator c)

Increment or decrement operator : ++ or -- : x=1; y=x++; (y=1,x=2) y=++x; (y=2,x=2)

rslt = expr1 ? expr2 : expr3 : if(expr1) rslt=expr2; else rslt=expr3;

while (expression) {..... statements ......}

for (expr1;expr2; expr3) {..... statements ......} : DO nn i=i1,in,id

expr1; while (expr2) {..... statements ..... expr3;}

do {..... statements .....} while (exprs)

if(exprs) {..... statements .....}

if(exprs) {..... statem1 .....} else {..... statem2 .....}

switch(exprs) {case valu1 : statem1 break; case valu2 : statem2 break; ..... case valun : statemn break; default : statemd break;}

break

continue

goto label1; label1: statement;

sizeof(item) : in <stdlib.h>

sizeof : memmory size of item in bytes

strlen : length of character string

strcpy : copy a character string

strcat : join two strings into one

strcmp : compare two character strings

strchr : position of a char in string

exit(n) : n=0 for normal termination

scanf("format", &item1, &item2, ......, &itemn)

printf("format", item1, item2, ......, itemn)

format : strings and %d %o %x %f %e %c %s

%5d %7.4f %9.3e

* : skip

\0 : null character

\a : alert (bell)

\b : back space

\f : form feed

\n : new line

\r : carriage return

\t : horizontal tab

\v : vertical tab

\\ : back slash

\" : double quotation mark

\' : single quotation mark

\ : line continue

\nnn : octal

\more

type sub1 (par1, par2)

{ ......... ;

....... ; }

type sub2 (par.....)

{ ......... ;

....... ; return; }

type sub3 (par......)

{ ......... ;

....... ; return expression; }

Standard functions ()

int getchar() int putchar()

char *gets(string) char *puts(string)

printf (fmt, par1, par2, ...) scanf (fmt, par1, par2, ...)

FILE *fopen(filename, filemode)

int fclose(ubitname)

int getc() int putc()

char *fgets() char fputs()

int ungets()

int fscanf() int fprint()

int fread() int fwrite()

fseek()

ftell()

FILE *unit, *fopen()

unit = fopen("filename", "r")

"r" "w" "a" "r+" "w+" "a+" ; (read-write)

"rb" "wb" "ab" ; (binary)

stdin :0: standard input file

stdout :1: standard output file

stderr :2: standard error file

fprintf(stdout, , , , ) = printf( , , , )

fscanf(stdin, , , , ) = scanf( , , , )

in math.h

double sin(double x)

cos

tan

asin

acos

atan

atan2(double x, double y) : atan(x/y)

double sinh(double x)

cosh

tanh

exp

log

log10

sqrt

power(double x, double y) : x^y

double ceil(double x)

double floor(double x)

int abs(int x)

int rand()

Compile and Link

cc -o filexec filename.c

g77 -o filexec filename.c