reversedString.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void input(char *str);
void reversedString(char *str, char* output);
void reversedSentence(char *sentenceProblem,char *solvedSentenceProblem);
int sentenceLength(char *sentence);
char* getSecondWordPointer(char *sentence);
void getFirstWord(char *sentenceProblem, char *firstWord);



int main()
{
	char str[100];
	char reversedStr[1000];
	input(str);
	//reversedString(str, reversedStr);
	reversedSentence(str, reversedStr);
	
	printf("%s\n", reversedStr);
	system("pause");
	return 0;
}


void input(char *str)
{
	//scanf("%s", str);
	gets(str);
}


void reversedString(char *question, char* output)
{
	if(strlen(question)>1){
		//general case
		//step1: 切割問題 
		char smallerQuestion[100];
		strcpy(smallerQuestion, question+1);
		char solvedQuestion[100];
		reversedString(smallerQuestion, solvedQuestion);
		//step2: 處理問題 
		strcpy(output, solvedQuestion);
		strncat(output, question, 1);
	}else{
		//解決最小的問題 
		strcpy(output, question);
	}
}

int  sentenceLength(char *sentence)
{
	char str[1000];
	strcpy(str, sentence);
	//printf("sentence=%s\n", sentence);
	int length = 0;
	char * pch;
	pch = strtok (str," ");
	while (pch != NULL)
	{
		length++;
		pch = strtok (NULL, " ");
	}
	//printf("length = %d\n", length);
	return length;
}

char* getSecondWordPointer(char *sentence)
{
	char str[1000];
	char * pch;
	
	//str = "hello world";
	strcpy(str, sentence);
	
	//str = "hello_world"; _ is \0
	//pch =  ^
	pch = strtok (str," ");
	
	//str = "hello_world"; _ is \0
	//pch =        ^
	pch = strtok (NULL, " ");
	
	size_t offset = pch-str;
	return sentence + offset;
}

void getFirstWord(char* sentenceProblem, char* firstWord)
{
	char str[1000];
	char * pch;
	strcpy(str, sentenceProblem);
	
	pch = strtok (str," ");
	strcpy(firstWord, pch);
}


void reversedSentence(char *sentenceProblem,char *solvedSentenceProblem)
{
	if(sentenceLength(sentenceProblem)>1){
		//general case
		//step1: 切割問題 
		char smallerQuestion[100];
		strcpy(smallerQuestion, getSecondWordPointer(sentenceProblem));
		char solvedQuestion[100];
		reversedSentence(smallerQuestion, solvedQuestion);
		//step2: 處理問題 
		strcpy(solvedSentenceProblem, solvedQuestion);
		strcat(solvedSentenceProblem, " ");
		char firstWord[100];
		getFirstWord(sentenceProblem, firstWord);
		//printf("sentenceProblem=%s, firstWord=%s\n", sentenceProblem, firstWord);
		strcat(solvedSentenceProblem, firstWord);
	}else{
		//解決最小的問題 
		strcpy(solvedSentenceProblem, sentenceProblem);
	}

}