gudako's memo

scanf格式说明符遵循以下原则：

%[*][width][length]specifier

specifier	Description	Characters extracted
i	Integer	Any number of digits, optionally preceded by a sign (+ or -). Decimal digits assumed by default (0-9), but a 0 prefix introduces octal digits (0-7), and0x hexadecimal digits (0-f). Signed argument.
d or u	Decimal integer	Any number of decimal digits (0-9), optionally preceded by a sign (+ or -). d is for a signed argument, and u for an unsigned.
o	Octal integer	Any number of octal digits (0-7), optionally preceded by a sign (+ or -). Unsigned argument.
x	Hexadecimal integer	Any number of hexadecimal digits (0-9, a-f, A-F), optionally preceded by 0x or 0X, and all optionally preceded by a sign (+ or -). Unsigned argument.
f, e, g	Floating point number	A series of decimal digits, optionally containing a decimal point, optionally preceeded by a sign (+ or -) and optionally followed by the e or E character and a decimal integer (or some of the other sequences supported by strtod). Implementations complying with C99 also support hexadecimal floating-point format when preceded by 0x or 0X.
a
c	Character	The next character. If a width other than 1 is specified, the function reads exactly widthcharacters and stores them in the successive locations of the array passed as argument. No null character is appended at the end.
s	String of characters	Any number of non-whitespace characters, stopping at the first whitespace character found. A terminating null character is automatically added at the end of the stored sequence.
p	Pointer address	A sequence of characters representing a pointer. The particular format used depends on the system and library implementation, but it is the same as the one used to format %pin fprintf.
[characters]	Scanset	Any number of the characters specified between the brackets. A dash (-) that is not the first character may produce non-portable behavior in some library implementations.
[^characters]	Negated scanset	Any number of characters none of them specified as characters between the brackets.
n	Count	No input is consumed. The number of characters read so far from stdin is stored in the pointed location.
%	%	A % followed by another % matches a single %.

http://www.cplusplus.com/reference/cstdio/scanf/

printf格式说明符遵循以下原则：

%[flags][width][.precision][length]specifier

%[标志][宽度][.精度][长度]说明符

specifier	Output	Example
d or i	带符号的十进制整数	392
u	无符号的十进制整数	7235
o	无符号八进制数字	610
x	无符号十六进制整数	7fa
X	无符号十六进制整型（大写）	7FA
f	十进制浮点数，小写	392.65
F	十进制浮点数，大写	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	字符	a
s	字符串	sample
p	指针地址	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.	%

http://www.cplusplus.com/reference/cstdio/printf/

bit（二进制位）是计算机中的最小单位。

1字节=8bit

8个二进制数占1字节。

2个十六进制数占1字节。

int声明的变量占4个字节。

 

二进制最高位表示正负。其中，0表示正、1表示负。

十六进制数最高位大于等于8时，必然是负数。

使用unsigned int声明变量时，不考虑符号，只取0和正数。

 

argc：arg为参数，c为计数器。

argv：arg为参数，v为值（value）

char：字符。占用1字节，8个位。

 

#include <stdio.h>

int main(int argc, char *argv[])
{
	int a = 0xFFFFFFFF;
	int b = 0x0FFFFFFF;

	printf("%d\t%u\n", a,a);
	printf("%d", b);

	return 0;
}

 

 

一、编译

编译是指把高级语言转化为机器语言的动作。

二、编译器

Windows平台——cl

Linux平台——gcc

Mac平台——clang

三、常见的集成开发环境

Windows平台——Visual Studio

Mac平台——Xcode

跨平台编译——Eclipse、Eclipse+CDT（开发C、C++）、CLion

#include <stdio.h>

int main(int argc,char *argv[])
{
	printf("hello,world\n");

	return 0;
}