Ji Geng 45 / 90

Random thoughts on programming

Bash function

1.Bash  There are two kinds of syntax for function definition .
#  The first one is 
fn() {
  # codes
}

#  The second kind 
function fn() {
  # codes
}

2. Parameter variable 
$1~$9： From the first to the 9 Parameters of .
$0： The name of the script where the function is located .
$#： The total number of arguments to the function .
$@： All the parameters of the function , Parameters are separated by spaces .
$*： All the parameters of the function , Use variables between parameters $IFS The first character of the value is separated by , Default is space , But you can customize .

3.return Command is used to return a value from a function , If the command line executes the function directly , You can give me a command $? Get the return value 
function func_return_value {
  return 10
}
$ func_return_value
$ echo "Value returned by function is: $?"
Value returned by function is: 10

4.Bash  Variables declared directly in the body of a function , Belongs to global variable , The entire script can be read . This requires special care .
 You can use local The command declares local variables .

Python Loops and lists

for i in list:
  print(i)

i = 0
while i < 5:
  print(i)
  i+=1
  
for i in range(0,6):
  print(i)

list = [1,2,3]
for i in list:
  print(i)
print(list[0])