遍历字符串，遇到空格就替换

C++ 代码

class Solution {
public:
    string replaceSpaces(string &str) {

        for (int i = 0; i < str.size(); i++) {
            if (str[i] == ' ') {
                str.replace(i,1,"%20");
            }
        }
        return str;
    }
};