Printf formatting output details

The general format of printf () format conversion is as follows: % (Flags) (width) (. Prec) Type Parameters enclosed in parentheses are optional parameters, while % and type are necessary. Next we will first introduce several types The integer % d is converted into a signed decimal number. The % u integer is converted to an unsigned decimal number. The % O integer is converted into an unsigned octal number. The % x integer is converted to an unsigned hexadecimal number and expressed in lowercase abcdef. The % x integer is converted into an unsigned hexadecimal number, and abcdef is used to represent the floating point number. The parameter of the % F double type is converted to a decimal number and rounded to six digits below the decimal point. Parameters of the % E double type are printed in an exponential form. There is a number that is before the decimal point, the six digits are after the decimal point, and the exponent part is expressed in lowercase E. % E has the same effect as % E. The only difference is that the exponent part is expressed by an uppercase E. Parameters of the % G Double type are automatically printed in the format of % f or % E. The standard is determined based on the value to be printed and the specified number of valid digits. The difference between % G and % G is the same. The only difference is that % E format is used for exponential printing. Character and string % C Integer Parameters are converted to the unsigned char type for printing. The parameter % s pointing to the string will be output verbatim until null characters appear. % P if the parameter is a void * pointer, it is displayed in hexadecimal format. Prec has several situations 1. The minimum number of digits of a positive integer. 2. represents the number of decimal places in the floating point type 3.% G represents the maximum number of valid digits. 4.% s represents the maximum length of the string. 5. If it is a * symbol, the value of the next parameter is the maximum length. Width is the minimum length of the parameter. If this column is not a value but a * symbol, it indicates that the next parameter is used as the parameter length. Flags has the following situations: + When a negative number is printed, printf () prints a negative number. This flag adds a positive sign (+) before the positive number is printed ). # This flag has different meanings based on the converted characters. Before the type is O (for example, % # O), a 0 value is printed before the octal value (indicating the octal value ). Before the type is X (% # X), '0x 'is printed multiple times before the hexadecimal number is printed ', before the type is E, E, F, G, or G, a numeric value is forced to print the decimal point. When the type is g or G, the zero at the end of the decimal point and decimal point is also reserved. 0 when a specified parameter exists, the parameter without a number is set to 0. This flag is disabled by default, so white spaces are usually printed. I recently reviewed the C language and found many previous knowledge points. I found them and reproduced an article with a very careful explanation. Printf format output Keywords: Printf Format code A ABC Abcdefgh % S A ABC Abcdefgh % 5s #### # ABC Abcdefgh %. 5 S A ABC ABCDE % 5.5 s #### # ABC ABCDE %-5 S A #### ABC ## Abcdefgh Printf format string Format code 1 -12 12345 123456789 % D 1 -12 12345 123456789 % 6d ##### 1 ###-12 #12345 123456789 %. 4D 0001 -0012 12345 123456789 % 6.4d #0001 #-0012 #12345 123456789 %-4d 1 #### -12 # 12345 123456789 % 04d 0001 -012 12345 123456789 % + D + 1 -12 + 12345 + 123456789 Printf format integer values Format code 1 . 01 . 00012345 12345.6789 % F 1.000000 0.010000 0.000123 12345.678900 % 10.2d ##### 1.00 #### 0.01 ##### 0.00 #12345.67 % E 1.000000e + 00 1.000000e-02 1.234500e-04 1.234568e + 04 %. 4e 1.20.e + 00 1.20.e-02 1.2345e-04 1.2127e + 04 % G 1 0.01 0.00012345 12345.7 Format code 6.023e23   % F 60229999999999975882752.000000   % 10.2e 60229999999999975882752.00   % E 6.023000e + 23   %. 4e 6.0230e + 23   % G 6.023e + 23   The format parameter is a string containing three object types: * Copy the unformatted characters to the output stream. * Conversion specification. Each specification causes zero or more items to be retrieved in the value parameter list. * The following escape sequence. When copying data to the output stream, these sequences cause their related operations to be displayed on devices with this function: \ Backslash \ A warning \ B Return \ F form feed \ N line feed \ R press ENTER \ T skip \ V vertical hop \ DDD is a one, two, or three-digit octal digit. These escape sequences are displayed as bytes with numeric values specified by the octal number.