Detailed explanation of the usage and differences of break, continue, pass and else in Python

python There are two circular reserved words in ：break and continue.

• effect ： Loop execution of auxiliary control program .
• break Statement and continue The difference between sentences ：break Statement is the process of ending the whole loop , It is not necessary to judge whether the condition for executing the loop is true ;continue Statement is to end only this loop , Does not terminate the execution of the entire loop .

1. break

• effect ： Used to jump out of the innermost layer for Loop or while loop , After leaving the loop, the program continues to execute after the loop code . namely break Statement can only jump out of the loop of the current level .

• Example ：

for i in "python":
for j in range(5):
print(i, end="")
if i == "t":
break
# The result of program execution is ：pppppyyyyytooooonnnnn

This example shows ,break The statement jumps out of the innermost for loop , But you can also perform an outer loop .

2. continue

• effect ： End the current cycle , That is, jump out of the statement that has not been executed in the loop body , But it doesn't jump out of the current loop .
• Example ：

for i in "python":
if i == "t":
continue
print(i, end="")
# The result of program execution is ：pyhon

for i in "python":
if i == "t":
break
print(i, end="")
# The result of program execution is ：py

3. pass

• effect ： Do nothing , It only plays a role of occupying . Use in loop pass Don't jump out of the loop
• Example ：

for i in "python":
if i == "t":
pass
print(i, end="")
# The result of program execution is ：python

4. for Circulation and while In the loop else Extended usage

• explain ：else The program in is executed under only one condition , That is, the loop normally traverses all contents or ends the loop because the condition does not hold , There is no reason break perhaps return And out of the loop .continue Yes else No impact
• Example ：

for i in "python":
if i == "t":
continue
print(i, end="")
else:
print(" Program exit normally ")
# The result of program execution is : pyhon Program exit normally 

for i in "python":
if i == "t":
break
print(i, end="")
else:
print(" Program exit normally ")
# The result of program execution is : py

matters needing attention ： Remember break Statement and continue The difference between sentences

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