Python正则表达式验证十进制数字

1. Find any positive integer decimal number without a leading zero in a larger body of text
\b(0|[1-9][0-9]*)\b

2. Check whether a text string holds just a positive integer decimal number without a leading zero
\A(0|[1-9][0-9]*)\Z

3. Find any positive integer decimal number without a leading zero standalone in a larger body of text
(?:^|(?<=\s))(0|[1-9][0-9]*)(?=$|\s)