python - 时间有问题。睡觉

Question

例如，当我运行时：

print("[",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("=",end=" ")
time.sleep(1)
print("]",end=" ")

10 秒内什么都没有发生，然后整个 [ = = = = = = = = = = ] 出现。我怎样才能防止这种情况，以便它可以充当一种进度条？

Answer 1

每次打印后尝试刷新标准输出：

import sys

print("=",end=" ")
sys.stdout.flush()

Answer 2

实际上，进度条属于sys.stderr，它（非常方便且并非巧合）没有缓冲。所以我建议你：

print("=", end=" ", file=sys.stderr)

反而。

PS a synopsis of the standard input, output and error streams in POSIX-conformant operating systems can be found in Wikipedia: Standard streams. In a few words: stdin is the input to a process; stdout is the useful output of a process, the results; stderr is for warnings, errors and out-of-band (e.g. progress bars) output.

Answer 3

sys.stdout.flush()

Answer 4

每次要写入更新时都需要刷新stdout使用。sys.stdout.flush()