C language format input and output functions

1. Format output function printf ()

1. The invocation form is generally: printf(" format control string ", output table column);

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

1. Format specifier: specifies the output format of the contents of the corresponding output table column, starting with %, such as %d, %o, etc
2. Escape character: to output the control code or special characters represented by escape character, such as' \n' and '\t'.
3. Ordinary characters: characters that need to be output as is.
3. The output table lists a number of data items that need to be output, which corresponds to the format specifier in terms of quantity and type.

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

-- indicates left alignment. L is used for long integer data. It can be added before d, o, x, and u.

Format characters	The data object	The output form	Data output method
% ( + ) -md	int unsigned int short unsigned short char	Decimal integer	1 And no m Output in actual digits   2 And there are m The output m A; More than m Bit, according to the actual number of output, not enough space   3 And there are + (the default is + ) align right (left padding)   4 And there are - Left alignment (right padding)
% ( + ) -mo		Octal integer
%(+)-mx		Hexadecimal integers
%(+)-mu		Unsigned integer
%(+)-mld	long unsigned long	Decimal integer
%(+)-mlo		Octal integer
%(+)-mlx		Hexadecimal integers
%(+)-mlu		Unsigned integer
%(+)-m.nf	float double	Decimal decimal
%(+)-m.ne		Decimal index
%(+)-g		Automatically choose %f and %e Short output widths for single - and double-precision floating - point Numbers
%(+)-mc	char int short	A single character	1 And no m Output single character 2 And there are m The output m Bit, fill space 3 And there are + (the default is + ) align right (left padding) 4 And there are - Left alignment (right padding)
%(+)-m.ns	string	A string of characters	1. There is no m , n Output all characters as actual strings 2 And there are m , n Just before the output n Characters, space padding 3. There are + (the default is + ) align right (left padding) 4 And there are - Left alignment (right padding)

Two: format input function scanf ()

1. The calling format is generally scanf (" format control string ", address table column);

2. The format control string has the same meaning as the printf () function, except that it controls the input format.

3, address table column is a number of data waiting for input of the corresponding memory location, separated by a comma, the general form is &a, a is a variable;

4. The address list in terms of quantity and type corresponds to the format specifier in the format control string.

5. The format character h represents the input short data, which can be used in front of d, o and x. M specifies the width of input data.

* means that the corresponding data item is not assigned to the corresponding variable after it is read in. More format specifiers and their combinations are shown below

Format characters	The data object	The input form	Data entry method
%md	int short unsigned int unsigned short	Decimal integer	1 And no m Enter in actual digits   2 And there are m The input m Insufficient place, m Then follow the enter key
%mo		Octal integer
%mx		Hexadecimal integers
%mld	long unsigned long	Decimal integer
%mlo		Octal integer
%mlx		Hexadecimal integers
%mlf	float double	Decimal integer
%mle
%mc	char	A single character	1 And no m Take a single character 2 And there are m The input m Bit, just take the first character
%ms	string	A string of characters	1 And no m A number of characters before retrieving the car or space 2 And there are m Just before taking m character

That's all for this article, I hope you enjoy it.