Keywords in C

    auto
    break
    case
    char
    const
    continue
    default
    do

    double
    else
    enum
    extern
    float
    for
    goto
    if

    int
    long
    register
    return
    short
    signed
    sizeof
    static

    struct
    switch
    typedef
    union
    unsigned
    void
    volatile
    while

C99 adds five more keywords:

    _Bool
    _Complex
    _Imaginary
    inline
    restrict

C11 adds seven more keywords:

    _Alignas
    _Alignof
    _Atomic
    _Generic
    _Noreturn
    _Static_assert

Placeholders - format specifiers

    %d - int (same as %i)
    %ld - long int (same as %li)
    %f - float
    %lf - double
    %c - char
    %s - string
    %x - hexadecimal

NOTES :

    %d     (print as a decimal integer)
    %6d    (print as a decimal integer with a width of at least 6 wide)
    %f     (print as a floating point)
    %4f    (print as a floating point with a width of at least 4 wide)
    %.4f   (print as a floating point with a precision of four characters after the decimal point)
    %3.2f  (print as a floating point at least 3 wide and a precision of 2)

    %e 	Display the floating point number using scientific notation with e
    %E 	Like e, but with a capital E in the output
    %g 	Use shorter of the two representations: f or e
    %G 	Like g, except uses the shorter of f or E

Escape Sequences :


    \n (newline)
    \t (tab)
    \v (vertical tab)
    \f (new page)
    \b (backspace)
    \r (carriage return)