编程常用资料收集
文章目录
ascii码表
c语言取整与四舍五入
floor函数
向下取整。floor(x)返回的是x的整数部分。如： floor(2.5) = 2 floor(-2.5) = -3
ceil函数
向上取整。ceil(x)返回的是不大于x的最小整数。如： ceil(2.5) = 3 ceil(-2.5) = -2 floor和ceil对于正数没有区别，但是对于负数结果不同。floor()是向负无穷大舍入，floor(-2.5) = -3；ceil()是向正无穷大舍入，ceil(-2.5) = -2。
round(x) 返回x的四舍五入整数值。
printf格式符
| length | d i | u o x X | f F e E g G a A | c | s | p | n |
|---|---|---|---|---|---|---|---|
| (none) | int | unsigned int | double | int | char* | void* | int* |
| hh | signed char | unsigned char | signed char* | ||||
| h | short int | unsigned short int | short int* | ||||
| l | long int | unsigned long int | wint_t | wchar_t* | long int* | ||
| ll | long long int | unsigned long long int | long long int* | ||||
| j | intmax_t | uintmax_t | intmax_t* | ||||
| z | size_t | size_t | size_t* | ||||
| t | ptrdiff_t | ptrdiff_t | ptrdiff_t* | ||||
| L | long double |
注：此表格说明了各种控制符及其长度符号的各种组合及适用对象，比如%ld用于long int符号，而
printf格式符释义
| 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. | % |