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What are the differences between the data types in this C language code?

int printf(const char *format,[argument]);

format

The format of parameter output, the definition format is: %[flags][width ][.perc][F|N|h|l]type

Specifies the data output method, as follows:

1. The meaning of type is as follows:

d Signed decimal integer

i Signed decimal integer

o Unsigned octal integer

u Unsigned decimal integer< /p>

x Unsigned hexadecimal number, expressed in lowercase abcdef

X Unsigned hexadecimal number, expressed in uppercase ABCDEF

f Float Point number

E/e Floating point number in scientific notation format

g Use %f and %e to express the shortest total number of digits to represent floating point number G. Same as g format , but expressed as an exponent

c single character

s string

S wchar_t character (wide character) type string

% Display the percent sign itself

p Display a pointer, the near pointer is represented as: XXXX

The far pointer is represented as: XXXX: YYYY

n The connected parameter should be A pointer that stores the number of written characters

2.flags specifies the output format. The values ??and meanings are as follows:

No right alignment, padded with 0s and spaces on the left

- Left-justified, padded with spaces on the right

+ Add the symbol + or - before the number

0 Add 0 in front of the output until the specified column width is filled (Cannot be used together with -)

When the space output value is positive, it is preceded by a space, and when it is negative, it is preceded by a minus sign

# When type=c,s,d,i, There is no effect when u

When type=o,x,X, add '0', "0x", "0X" in front of the value respectively

type=e,E,f When type=g,G, the decimal point is always displayed except when the value is 0

3.width is used to control the width of the displayed value, and the value is The meaning is as follows

n(n=1,2,3...) The width is at least n bits, which is not enough to fill with spaces

0n(n=1,2,3.. .) The width is at least n digits, and the left side is filled with 0 if it is not enough

* In the format list, the next parameter is width

4.prec is used to control the number of digits after the decimal point, take The values ??and meanings are as follows:

No display according to the default precision

0 When type=d,i,o,u,x, there is no effect

type =e,E,f, no decimal point is displayed

n(n=1,2,3...) The maximum number of decimal places expressed when type=e,E,f

type=other, indicating the maximum width of the display

.* In the format list, the next parameter is still width

5.F|N|h|l indicates whether the pointer is Whether the far pointer or integer is a long integer

F far pointer

n near pointer

h short integer or single-precision floating point number

l 长整数或双精度浮点数

以上内容参考:/view/410546.htm

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重点看 In the second line, [h] indicates that h is optional, but type is required. So it is wrong to just write h, because there is no type. And u is a type, so it’s OK.

It’s just a rule of C language, there’s no reason why haha.