字符串中的每个空格替换成“%20”

solution 1:

public class Solution {
    public String replaceSpace(StringBuffer str) {
        return str.toString().replace(" ", "%20");
    }
}

solution 2:

public String replace(StringBuffer str) {
        int n = str.length();
        for(int i=0; i<n; i++) {
            if(str.charAt(i) == ' ') {
                n += 2;
                str.replace(i, i+1, "%20");
            }
        }
        return str.toString();
    }

C++ solution:

class Solution {
public:
    void replaceSpace(char* str, int length) {
        string str_cpp(str);
        string::size_type pos = 0;
        while ((pos = str_cpp.find(' ')) != string::npos) {
            str_cpp.replace(pos, 1, "%20");
        }
        str = strcpy(str,str_cpp.c_str());
    }
};