练习7-2重循环

import random#判断一个6位随机数中是否包含4和7'''i=0while i<20:      x=random.randint(100000,1000000)      s=str(x)      if "4" in s and "7" in s:      #if '4' in   s and '7' in s:            print(s,"contain 4 and 7!")      else:            print(s,"not contain 4 and 7!")      i=i+1'''#判断一个6位随机数中是否包含4和7，并打印其位置i=0while i<5:      x=random.randint(100000,1000000)      s=str(x)      if "4" in s or "7" in s:            print(s)            k=0            while k<len(s):                  if s[k]=='4' or s[k]=='7':                        print(k,s[k])                  k=k+1            print('')      i=i+1