1.4 Write a method to replace all spaces in a string with '%20'. Youmay assume that the string has sufficient space at the end of the string to hold the additional characters, and that you are given the "true" length of the string. (Note: if implementing in Java, please usea character array so that you can perform this operation inplace.)

1.4.cpp

#include<iostream>

using namespace std;

void replace(char *s, unsigned l)
{
    if (s == nullptr) return;
    unsigned sp = 0;
    for (int i = 0; i < l; i++)
        if (s[i] == ' ')
            sp++;
    unsigned nl = l + 2*sp;
    s[nl] = '\0';
    for (int i = nl-1, j = l-1; j >= 0;) {
        if (s[j] != ' ')
            s[i--] = s[j--];
        else {
            s[i--] = '0';
            s[i--] = '2';
            s[i--] = '%';
            j--;
        }
    }
}

int main(int argc, char *argv[])
{
    char s[100] = " Mr John Smith       ";
    replace(s, 14);
    cout << s << endl;
    return 0;
}