import time
scale = 50
print("执行开始".center(scale//2,"-"))
start = time.perf_counter()
for i in range(scale + 1):
a = '*' * i
b = '.' * (scale - i)
c = (i/scale)*100
dur = time.perf_counter() - start
print("\r{:^3.0f}%[{}->{}]{:.2f}s".format(c,a,b,dur),end='')
time.sleep(0.3)
print("\n"+"执行结束".center(scale//2,'-'))