#coding:utf-8
#string are arrays(1次元配列)
import os 
import time

os.system("clear")

a="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
print(a,len(a))
print(a[-5],a[20],a[25],a[-15])

#for while

str=""
for i in range(0,len(a),1):
    str = a[i] +str
    print("\r"+str,end="")
    time.sleep(0.3)
print("\n")

str=""
i=-1
while i >= -len(a):
    str += a[i]
    print("\r"+str,end="")
    i -= 1
    time.sleep(0.3)
print("\n")

str=""
for i in range(-1,-len(a)-1,-1):
    str = a[i] 
    print("\r"+str,end="")
    time.sleep(0.3)
print("\n")

#スライス

print(a[2:10],a[-5: ],a[:7])#([0]は反応しない)

b=""
k=20
for i in range(0,len(a)-k,1):
    print("\r"+a[i:i+k],end="")
    time.sleep(0.3)

    k=20
for j in range(1,len(a),1):
    print("\r"+a[j:]+" ",end="")
    time.sleep(0.3)
print("\n")
        

実行結果