tips:
1.函數包含在stdio.h文件中，使用#include<stdio.h>
2.函數聲明：int sprintf( char *buffer, const char *format , [argument,...] );
3.主要功能是根據char *format定義格式輸出到字符串緩衝區buffer
sprintf主要是依靠控制格式的字符串const char *format 來完成靈活的寫入
format的用法跟printf函數的一樣，下面介紹printf的format結構
format的結構 %[flags][width][.precision][length]specifier
1.specifier
| specifier | Output | Example |
|---|---|---|
| d or i | Signed decimal integer | 392 |
| u | Unsigned decimal integer | 7235 |
| o | Unsigned octal | 610 |
| x | Unsigned hexadecimal integer | 7fa |
| X | Unsigned hexadecimal integer (uppercase) | 7FA |
| f | Decimal floating point, lowercase | 392.65 |
| F | Decimal floating point, uppercase | 392.65 |
| e | Scientific notation (mantissa/exponent), lowercase | 3.9265e+2 |
| E | Scientific notation (mantissa/exponent), uppercase | 3.9265E+2 |
| g | Use the shortest representation: %e or %f | 392.65 |
| G | Use the shortest representation: %E or %F | 392.65 |
| a | Hexadecimal floating point, lowercase | -0xc.90fep-2 |
| A | Hexadecimal floating point, uppercase | -0XC.90FEP-2 |
| c | Character | a |
| s | String of characters | sample |
| p | Pointer address | b8000000 |
| n | Nothing printed. The corresponding argument must be a pointer to a signed int.The number of characters written so far is stored in the pointed location. | |
| % | A % followed by another % character will write a single % to the stream. | % |
2.flags
| flags | description |
|---|---|
| - | Left-justify within the given field width; Right |
+ Forces to preceed the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign.
(space) If no sign is going to be written, a blank space is inserted before the value.
Used with o, x or X specifiers the value is preceeded with 0, 0x or 0X respectively for values different than zero.
Used with a, A, e, E, f, F, g or G it forces the written output to contain a decimal point even if no more digits follow. By default, if no digits follow, no decimal point is written.
0 Left-pads the number with zeroes (0) instead of spaces when padding is specified (see width sub-specifier).