Question

c++中%c是什么意思

c++中在输出后台信息的时候一直会用%d,%s,%c这些都是什么意思，都有哪些，我说的全了吗？
请说全，并给解释哦，谢谢

Answer 1

%c是格式控制符，意思是按字符输入或输出，比如：char ch='a';printf("%c\n",ch);那么就会输出a。

%d:输入输出为整形,printf("%d",a);也就是打印整数a.

%s:输入输出为字符串

%f:输入输出为浮点型

printf( stream, "%s%c", s, c );

%s -- 打印格式，按字符串方式输出变量s的值（字符串）到文件流stream

%c -- 打印格式，按ASCII字符方式输出变量c的值(即打印一个字符）到文件流stream

:在C++中有两种意思，一种是取地址符，是单目运算符；另一种是位运算符，表示“按位与”，是双目运算符。

a＆b表示a和b执行按位与运算。

＆后跟一个变量。每个变量对应一个存储空间块。每个存储空间都有一个数字，即地址，＆变量名表示取出该代码，而变量名表示取出该编号对应的存储空间中的值。

系统将在内存中分配一个空间，* a的值是变量a的值；定义一个指向整数数据的指针，效果与＆相反，它根据变量的地址获取变量的值，编译时给它分配一个地址，指针指向整数数据。

Answer 2

%c是格式控制符，意思是按字符输入或输出，比如：char ch='a';printf("%c\n",ch);那么就会输出a
%d:输入输出为整形,printf("%d",a);也就是打印整数a.
%s:输入输出为字符串
%f:输入输出为浮点型
printf( stream, "%s%c", s, c );
%s -- 打印格式，按字符串方式输出变量s的值（字符串）到文件流stream
%c -- 打印格式，按ASCII字符方式输出变量c的值(即打印一个字符）到文件流stream

printf( stream, "%f\n", fp ); %f 是浮点格式

Answer 3

%d,输出
%s,输出字符串
%c， 输出字符

printf Type Field Characters
Character Type Output format
c
int or wint_t
When used with printf functions, specifies a single-byte character; when used with wprintf functions, specifies a wide character.

C
int or wint_t
When used with printf functions, specifies a wide character; when used with wprintf functions, specifies a single-byte character.

d
int
Signed decimal integer.

i
int
Signed decimal integer.

o
int
Unsigned octal integer.

u
int
Unsigned decimal integer.

x
int
Unsigned hexadecimal integer, using "abcdef."

X
int
Unsigned hexadecimal integer, using "ABCDEF."

e
double
Signed value having the form [ – ]d.dddd e [sign]dd[d] where d is a single decimal digit, dddd is one or more decimal digits, dd[d] is two or three decimal digits depending on the output format and size of the exponent, and sign is + or –.

E
double
Identical to the e format except that E rather than e introduces the exponent.

f
double
Signed value having the form [ – ]dddd.dddd, where dddd is one or more decimal digits. The number of digits before the decimal point depends on the magnitude of the number, and the number of digits after the decimal point depends on the requested precision.

g
double
Signed value printed in f or e format, whichever is more compact for the given value and precision. The e format is used only when the exponent of the value is less than –4 or greater than or equal to the precision argument. Trailing zeros are truncated, and the decimal point appears only if one or more digits follow it.

G
double
Identical to the g format, except that E, rather than e, introduces the exponent (where appropriate).

a
double
Signed hexadecimal double precision floating point value having the form [−]0xh.hhhh p±dd, where h.hhhh are the hex digits (using lower case letters) of the mantissa, and dd are one or more digits for the exponent. The precision specifies the number of digits after the point.

A
double
Signed hexadecimal double precision floating point value having the form [−]0Xh.hhhh P±dd, where h.hhhh are the hex digits (using capital letters) of the mantissa, and dd are one or more digits for the exponent. The precision specifies the number of digits after the point.

n
Pointer to integer
Number of characters successfully written so far to the stream or buffer; this value is stored in the integer whose address is given as the argument. See Security Note below.

p
Pointer to void
Prints the address of the argument in hexadecimal digits.

s
String
When used with printf functions, specifies a single-byte–character string; when used with wprintf functions, specifies a wide-character string. Characters are printed up to the first null character or until the precision value is reached.

S
String
When used with printf functions, specifies a wide-character string; when used with wprintf functions, specifies a single-byte–character string. Characters are printed up to the first null character or until the precision value is reached.

Answer 4

123
13468467
46438154

Answer 5

字符型变量