面试题4：替换空格

知识点

char str1[] = "hello";
char str2[] = "hello";
char *str3 = "hello";
char *str4 = "hello";

// ReplaceBlank.cpp : Defines the entry point for the console application.
//

// 《剑指Offer——名企面试官精讲典型编程题》代码
// 著作权所有者：何海涛

#include "stdafx.h"
#include <string>

/*length 为字符数组string的总容量*/
void ReplaceBlank(char string[], int length)
{
if(string == NULL && length <= 0)
return;

/*originalLength 为字符串string的实际长度*/
int originalLength = 0;
int numberOfBlank = 0;
int i = 0;
while(string[i] != '\0')
{
++ originalLength;

if(string[i] == ' ')
++ numberOfBlank;

++ i;
}

/*newLength 为把空格替换成'%20'之后的长度*/
int newLength = originalLength + numberOfBlank * 2;
if(newLength > length)
return;

int indexOfOriginal = originalLength;
int indexOfNew = newLength;
while(indexOfOriginal >= 0 && indexOfNew > indexOfOriginal)
{
if(string[indexOfOriginal] == ' ')
{
string[indexOfNew --] = '0';
string[indexOfNew --] = '2';
string[indexOfNew --] = '%';
}
else
{
string[indexOfNew --] = string[indexOfOriginal];
}

-- indexOfOriginal;
}
}

void Test(char* testName, char string[], int length, char expected[])
{
if(testName != NULL)
printf("%s begins: ", testName);

ReplaceBlank(string, length);

if(expected == NULL && string == NULL)
printf("passed.\n");
else if(expected == NULL && string != NULL)
printf("failed.\n");
else if(strcmp(string, expected) == 0)
printf("passed.\n");
else
printf("failed.\n");
}

// 空格在句子中间
void Test1()
{
const int length = 100;

char string[length] = "hello world";
Test("Test1", string, length, "hello%20world");
}

// 空格在句子开头
void Test2()
{
const int length = 100;

char string[length] = " helloworld";
Test("Test2", string, length, "%20helloworld");
}

// 空格在句子末尾
void Test3()
{
const int length = 100;

char string[length] = "helloworld ";
Test("Test3", string, length, "helloworld%20");
}

// 连续有两个空格
void Test4()
{
const int length = 100;

char string[length] = "hello  world";
Test("Test4", string, length, "hello%20%20world");
}

// 传入NULL
void Test5()
{
Test("Test5", NULL, 0, NULL);
}

// 传入内容为空的字符串
void Test6()
{
const int length = 100;

char string[length] = "";
Test("Test6", string, length, "");
}

//传入内容为一个空格的字符串
void Test7()
{
const int length = 100;

char string[length] = " ";
Test("Test7", string, length, "%20");
}

// 传入的字符串没有空格
void Test8()
{
const int length = 100;

char string[length] = "helloworld";
Test("Test8", string, length, "helloworld");
}

// 传入的字符串全是空格
void Test9()
{
const int length = 100;

char string[length] = "   ";
Test("Test9", string, length, "%20%20%20");
}

int _tmain(int argc, _TCHAR* argv[])
{
Test1();
Test2();
Test3();
Test4();
Test5();
Test6();
Test7();
Test8();
Test9();

return 0;
}