知识储备：02数组与字符串：String相关问题

String相关问题

1.用特定的间隔符号将句子分隔成单词，倒转非数字的单词

2.替换特定字符

新字符串增长，从后往前赋值

新字符串剪短，从前往后赋值

代码如下：

#include <iostream>
#include <vector>
#include <unordered_map>
using namespace std;

/*
String相关问题
2017-8-21
*/

//1.反转句子
//判断间隔字符
bool isGap(char *c)
{
	return (*c == ' ' || *c == ',' || *c == '.');
}

//是否数字
bool isNumber(char *c)
{
	if (*c<'0' || *c>'9')
		return false;
	return true;
}

//是否需要反转
bool needReverse(char *sentence, int *offset)
{
	int length = strlen(sentence);
	bool needReverse = false;
	*offset = 0;
	while (!isGap(sentence + (*offset)) && (*offset) < length)
	{
		if (!isNumber(sentence + (*offset)))
		{
			needReverse = true;
		}
		(*offset)++;
	}
	return needReverse;
}

//反转单词
void ReverseWord(char *c, int length)
{
	int i = 0;
	int j = length - 1;
	while (i < j)
	{
		swap(c[i], c[j]);
		i++;
		j--;
	}
}

//反转句子
void reverseSentence(char *sentence)
{
	int length = strlen(sentence);
	int offset;
	for (int i = 0; i < length;)
	{
		if (needReverse(sentence + i, &offset))
		{
			ReverseWord(sentence, offset);
		}
		i += (offset + 1);
	}
}

//2.空格替换为%20

//检测特定字符，返回下标
int findChar(char *src, int index, char c)
{
	int len = strlen(src);
	for (int i = index; i < len; i++)
	{
		if (src[i] == c)
			return i;
	}
}



//空格替换为%20
char* replaceSpace(char *src)
{
	char *newStr;//新字符串
	char *repStr = "%20";
	
	int len = strlen(src);
	newStr = (char*)malloc(sizeof(char)*(len + 2));
	memset(newStr, 0, sizeof(char));
	int pos = strchr(src, ' ') - src;
	for (int i = len - 1; i > pos; i--)
		newStr[i + 2] = src[i];
	for (int i = 0; i < 3; i++)
		newStr[pos+i] = repStr[i];
	for (int i = 0; i < pos; i++)
		newStr[i] = src[i];

	return newStr;
}

//%20替换为空格
char* replace20(char *src)
{
	char *newStr;//新字符串
	char *repStr = " ";

	int len = strlen(src);
	newStr = (char*)malloc(sizeof(char)*(len - 2));
	memset(newStr, 0, sizeof(char));
	int pos = strstr(src, "%20") - src;
	for (int i = 0; i < pos; i++)
		newStr[i] = src[i];
	newStr[pos] = ' ';
	for (int i = pos + 1; i < len - 2; i++)
		newStr[i] = src[i + 2];

	return newStr;
}

int main()
{
	//char *c = "word";//字符串常量，无法修改，报错
	
	//字符数组
	char c[] = "word";
	ReverseWord(c, 4);
	cout << "采用字符数组反转后的单词："<< c << endl;
	
	//堆上开辟内存
	char *temp = "word";
	char *c1 = (char*)malloc(sizeof(char)*(strlen(temp) + 1));
	strcpy(c1, temp);
	ReverseWord(c1, 4);
	cout <<"采用堆上开辟内存反转后的单词：" << c << endl;
	//释放内存
	free(c1);
	cout << "c1内存已释放" << endl;

	char *str = "Big mac";
	str = replaceSpace(str);
	cout << "%20替换空格：" << str << endl;

	str = "Big%20mac";
	str = replace20(str);
	cout << "空格替换%20：" << str << endl;

	return 0;
}

运行结果：