按单词翻转字符串 C语言实现

最新推荐文章于 2023-12-20 20:46:49 发布

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本文介绍如何使用C语言来实现一个功能，即在不改变单词内部顺序的情况下，翻转字符串中的单词顺序。首先，整体翻转整个字符串，然后依次翻转每个单词内的字符顺序。

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先翻转整个字符串，再翻转每个单词。

#include <string.h>

void swap(char *left, char *right){
	char tmp = *left;
	*left = *right;
	*right = tmp;
}

void reverse(char *str, int begin, int end){
	while(begin < end){
		swap(&str[begin], &str[end]);
		++begin;
		--end;
	}
}

void reverseSentence(char *sentence){
	int len = strlen(sentence);
	int wordBegin = 0;
	int wordEnd = 0;
	if(sentence == NULL) return;
	reverse(sentence, 0, len - 1);
	while(sentence[wordBegin] == ' '){
		++wordBegin;
		++wordEnd;
	}
	while(sentence[wordEnd] != '\0'){
		while(sentence[wordEnd] != ' ' && sentence[wordEnd] != '\0'){
			++wordEnd;
		}
		reverse(sentence, wordBegin, wordEnd - 1);
		if(sentence[wordEnd] == '\0') break;
		wordBegin = wordEnd;
		while(sentence[wordBegin] == ' '){
			++wordBegin;
			++wordEnd;
		}
	}
}

int main(){
	char *cases[] = {"hello   world!!!", " hello world...", "  Hello  world???", "hello", "   ", " ", "hi I am lic."};
	char **str;
	int strIndex = 0;
	int letterIndex = 0;
	int casesNum = sizeof(cases) / sizeof(char*);
	str = (char**)malloc(sizeof(cases));
	for(strIndex = 0; strIndex < casesNum; ++strIndex){
		str[strIndex] = (char*)malloc(1 + strlen(cases[strIndex]));
		for (letterIndex = 0; letterIndex < strlen(cases[strIndex]); ++letterIndex)
		{
			str[strIndex][letterIndex] = cases[strIndex][letterIndex];
		}
		str[strIndex][letterIndex] = '\0';
	}
	for(strIndex = 0; strIndex < casesNum; ++strIndex){
		printf("before: %s\n", str[strIndex]);
		reverseSentence(str[strIndex]);
		printf("after : %s\n", str[strIndex]);
	}
	for(strIndex = 0; strIndex < casesNum; ++strIndex){
		free(str[strIndex]);
	}
	free(str);
	return 0;
}