%d is the output format controller of printf () function in C language, which means to output decimal signed integers.
% md: m is the width of the specified output field. If the number of digits of data is less than m, the left end is filled with spaces; If it is greater than m, it is output according to the actual number of digits.
Format controls always start with a format declaration, that is, with a% sign. You can insert a number between% and letters to indicate the maximum field width.
For example, %3d means to output a 3-bit integer, which is not enough for 3-bit right alignment.
Extended data:
Other formatting controls corresponding to %d:
1, %o format: output integers in unsigned octal format. Long integers can be output in "%lo" format. You can also specify the width of the field output in "%mo" format.
2.%x format: output integers in unsigned hexadecimal form. Long integers can be output in "%lx" format. You can also specify the field width and output it in "%mx" format.
3.%u format: output integers in unsigned decimal form. Long integers can be output in "%lu" format. You can also specify the field width to output in "%mu" format.
4.%c format: output a character.
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