+ ：
1 s1 = ‘a‘
2 s2 = ‘b‘
3 s3 = ‘c‘
4 s = ‘I have ‘ + s1 +‘, ‘ + s2 + ‘, ‘ + s3
5 输出： ‘I have a, b, c‘
%：
1 s1 = ‘a‘
2 s2 = ‘b‘
3 s3 = ‘c‘
4 s = ‘I have %s, %s, %s‘%(s1, s2, s3)
5 输出： ‘I have a, b, c‘
.format：
1 s1 = ‘a‘
2 s2 = ‘b‘
3 s3 = ‘c‘
4 s = ‘I have {}, {}, {}‘.format(s1, s2, s3)
5 输出： ‘I have a, b, c‘
推荐使用 .format 和 %方式拼接字符串。
原文：https://www.cnblogs.com/yangwu-183/p/10035746.html