我在try 理解，如果我删除I Get Error，为什么我们需要冒号. 我正在努力了解更多关于弦的知识
string = "welcome to the world of python programming";
print("Duplicate characters in a given string: ");
for i in range(0, len(string)):
count = 1;
for j in range(i+1, len(string)):
if(string[i] == string[j] and string[i] != ' '):
count = count + 1;
string = string[:j] + ' ' + string[j+1:];
if(count > 1 and string[i] != '0'):
print(string[i]," - ",count)