类型转换和舍入

类型转换

转化为int整型

int(<var>)

a = 3.1415926
print(int(a))
# 3

转化为float浮点型

float(<var>)，最多保留16位有效数字

例子1

a = 6
b = float(a)
print(b)
# 6.0

例子2

a = 6.12345
b = float(a)
print(b)
# 6.12345

例子3

a = 6.123456789012345
b = float(a)
print(b)
# 6.123456789012345

例子4

a = 6.1234567890123456789
b = float(a)
print(b)
# 6.123456789012345  
# 超出精度的部分被社区，仅保留16位有效数字

*转化为complex复数型

complex(<var>, <var>

例子1

a = complex(2)
b = complex(0,3)
c = complex(2,3)
print(a)
print(b)
print(c)

# (2+0j)
# 3j
# (2+3j)

例子2

a = complex(2)
b = complex(0,3)
c = complex(2,3)
if a+b == c:
    print('a+b和c等价')
# a+b和c等价  

舍入（四舍五入）

round(<var>, <precision>)

<var>被四舍五入的值，<percision>小数点后保留的位数

例子1(四舍)

a = 6.123
b = round(a, 2)
print(b)
# 6.12

例子2(五入)

a = 6.11171
b = round(a, 3)
print(b)
# 6.112