C-formatted input-output functions

One: Format output function printf ()

1, the call form is generally: printf ("Format control string", output table column);

2. The format control string is used to specify the output format, which has three forms:

• 1. Format specifier: Specifies the output format of the corresponding output table column, with a% beginning, such as%d,%o, etc.
• 2. Escape character: Used to output the control code or special characters that the escape character represents, such as the usual ' \ n ', ' \ t '
• 3. Ordinary characters: characters that need to be output as-is.

3, the output table is listed as several data items that need to be output, and it corresponds to the format specifier one by one on the quantity and type;

4, the format character m specifies the width of the output data, n for the real number represents the output n decimal places, the string represents the amount of characters intercepted, + the right alignment, usually omitted.

-Indicates left alignment, L is used for long integer data, can be added to D, O, X, U, and more format specifiers and their combined form are as follows:

Format characters	Data Objects	Output form	Data Output method
% (+)-MD	Int unsigned int Short unsigned short Char	Decimal integer	1, no m output according to the actual number of digits 2, have m output m bit, more than M bit, according to the actual number of output, insufficient space to fill 3. have + (default = +) Right align (left fill space) 4, have-left alignment (right fill space)
% (+)-mo		Eight-binary integers
% (+)-mx		hexadecimal integer
% (+)-mu		unsigned integer
% (+)-MLD	Long unsigned long	Decimal integer
% (+)-mlo		Eight-binary integers
% (+)-MLX		hexadecimal integer
% (+)-mlu		unsigned integer
% (+)-m.nf	Float Double	Decimal decimal
% (+)-m.ne		Decimal index
% (+)-G		Automatically selects short output widths in%f and%e to output single, double-precision floating-point numbers
% (+)-MC	Char Int Short	Single character	1. No m output single character 2, with m output m bit, fill space 3. have + (default = +) Right align (left fill space) 4, have-left alignment (right fill space)
% (+)-m.ns	String	A string of characters	1. No m, n output all characters by actual string 2, have m, n only output the first n characters, fill the space 3. have + (default = +) Right align (left fill space) 4, have-left alignment (right fill space)

Two: Format input function scanf ()

1, the call format is generally: scanf ("Format control string", Address table column);

2, the format control string and the printf () function similar meaning, the difference is that it is the input format control;

3, the Address table column is a number of data waiting for input corresponding to the memory unit address composition, separated by commas, the general form of &a,a as a variable;

4, the Address table column in the number and type and format control string in the format specifier one by one corresponds;

5, the format character H denotes the input short data, can be used in the D, O, x front, m specifies the width of the input data,

* indicates that the corresponding data item is not assigned to the corresponding variable after it is read, more format specifiers and their combinations are as follows

Format characters	Data Objects	Input form	Data entry Methods
%md	Int Short unsigned int unsigned short	Decimal integer	1, no m input according to the actual number of digits 2, have m input m bit, less than m followed by enter
%mo		Eight-binary integers
%mx		hexadecimal integer
%mld	Long unsigned long	Decimal integer
%mlo		Eight-binary integers
%mlx		hexadecimal integer
%mlf	Float Double	Decimal integer
%mle
%mc	Char	Single character	1. No m takes a single character 2, have m input m bit, only take the first character
%ms	String	A string of characters	1, no m to retrieve the car or a number of characters before the space 2, have M only take the first m character

C-formatted input-output functions