test_concate.py

print "\nadding string variables\n"
a = "zhi"
b = "hu"
c = "yao"
d = "xxx"
print a+b+c+d

print "\nadding string literals\n"
print "zhi" + "hu" + "yao" + "xxx"

"""
Output:

adding string variables


calling string_concatenate
no place for resizing, will call string_concat

calling string_concatenate

calling string_concatenate
zhihuyaoxxx

adding string literals

zhihuyaoxxx

"""