JZ-C-04

剑指offer第四题：字符串中替换空格

//============================================================================
// Name        : JZ-C-04.cpp
// Author      : Laughing_Lz
// Version     :
// Copyright   : All Right Reserved
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <string.h>
#include <string>
using namespace std;

char* ReplaceBlank(char string[]) {
    int length = strlen(string);
    if (length > 0) {
        int number = 0; //初始化
        for (int i = 0; i < length; i++) {
            if (string[i] == ' ') {
                number++; //先记录空格数
            }
        }
        int newLength = length + number * 2; //重新定义字符串长度
        char* result = new char[newLength]; //定义新的字符串
        char *p, *q; //定义两个指向两字符串的指针
        p = string;
        q = result;
        int pIndex = length - 1; //从字符串末尾向前依次输出，遇到空格，转换为%20
        int qIndex = newLength - 1;
        while (pIndex >= 0 && qIndex >= 0) {
            if (p[pIndex] == ' ') {
                q[qIndex--] = '0';
                q[qIndex--] = '2';
                q[qIndex--] = '%';
                pIndex--;
            } else {
                q[qIndex--] = p[pIndex--];
            }
        }
        q[newLength] = '';//最后补位''
        return result;
    } else {
        cout << "字符串为空" << endl;
        return NULL;
    }
}
int main() {
    char string[] = "Hello World ";
    char* result = ReplaceBlank(string);
    cout << "转换后：" << result << endl;
    delete[] result;//释放内存，针对函数里的char* result =new char[...] ?
    return 0;
}