a - NUL 填充的字符串
A - SPACE 填充的字符串
h - 十六进制字符串,低位在前
H - 十六进制字符串,高位在前
c - signed char
C - unsigned char
s - signed short(总是16位, machine 字节顺序)
S - unsigned short(总是16位, machine 字节顺序)
n - unsigned short(总是16位, big endian 字节顺序)
v - unsigned short(总是16位, little endian 字节顺序)
i - signed integer(取决于machine的大小和字节顺序)
I - unsigned integer(取决于machine的大小和字节顺序)
l - signed long(总是32位, machine 字节顺序)
L - unsigned long(总是32位, machine 字节顺序)
N - unsigned long(总是32位, big endian 字节顺序)
V - unsigned long(总是32位, little endian 字节顺序)
f - float(取决于 machine 的大小和表示)
d - double(取决于 machine 的大小和表示)
x - NUL 字节
X - 备份一个字节
Z - NUL 填充的字符串
@ - NUL 填充绝对位置
a - NUL 填充的字符串
A - SPACE 填充的字符串
h - 十六进制字符串,低位在前
H - 十六进制字符串,高位在前
c - signed char
C - unsigned char
s - signed short(总是16位, machine 字节顺序)
S - unsigned short(总是16位, machine 字节顺序)
n - unsigned short(总是16位, big endian 字节顺序)
v - unsigned short(总是16位, little endian 字节顺序)
i - signed integer(取决于machine的大小和字节顺序)
I - unsigned integer(取决于machine的大小和字节顺序)
l - signed long(总是32位, machine 字节顺序)
L - unsigned long(总是32位, machine 字节顺序)
N - unsigned long(总是32位, big endian 字节顺序)
V - unsigned long(总是32位, little endian 字节顺序)
f - float(取决于 machine 的大小和表示)
d - double(取决于 machine 的大小和表示)
x - NUL 字节
X - 备份一个字节
Z - NUL 填充的字符串
@ - NUL 填充绝对位置