C语言 字符串分割

大家好，又见面了，我是你们的朋友全栈君。

                                                         C语言 字符串分割

一、简述
        记–字符串分割，strtok()函数的使用例子、自己简单实现split()函数。

二、例子代码

#include <stdio.h>
#include <string.h>
 
/*
 * 函数:split
 * 描述:按指定分隔符分割字符串
 * 参数:
 *		str:要分割的字符串
 *		strLen:要分割的字符串的长度
 * 		splitChar:分隔符
 * 		index:获取第几部分, 1<=index
 *		result:结果字符串, result = str[index-1];
 * 		maxLen:指定结果的最大长度
 * 返回值:
 *		>=0:成功, 结果长度
 * 		其它:失败
 * 例子:
 *		split("11;22;33", 8, ';', 2, result. 16);
 *		结果result是:22.
 */
int split(const char* str, int strLen, const char* splitChar, int index, char* result, int maxLen)
{
	int i = 0;
    int ret = 0;	
	int findLen = 0;
	int findFlag = 0;	
	int startIndex = 0;
	int splitCharLen = 0;
	
	//合法性判断
	if(NULL == str || NULL == result || NULL == splitChar || index<=0)
	{
		return -1;
	}		
	splitCharLen = strlen(splitChar);
	findLen = strLen-splitCharLen;
	if(findLen<0)
	{
		return -2;
	}	
	
	//查找结果的左右分隔符位置
	for(; i<=findLen && str[i] != '\0'; i++)
	{
		if(strncmp(&str[i], splitChar, splitCharLen) == 0)
		{
			if(0 == findFlag)//find the left
			{
				startIndex++;
				if(1 == index)//第一个直接返回
				{
					strncpy(result, &str[0], i);
					ret = i;
					break;
				}
				else if(startIndex+1 == index)
				{
					startIndex = i;
					findFlag = 1;
				}
			}
			else//find the right
			{
				findFlag = 2;
				break;
			}
		}
	}	
	
	//截取结果
	if(0 != findFlag && startIndex<strLen-1)
	{
		startIndex += splitCharLen;
		ret = i-startIndex;//结果的字符个数
		if(ret>maxLen || ret>strLen)
		{
			ret = 0;
		}
		else if(ret>0)
		{
			strncpy(result, &str[startIndex], ret);
			ret = strlen(result);
		}
	}
	return ret;
}
 
int main(void)
{	
	{
		const char* splitChar = ";";
		printf("\n==========strtok1==========\n");
		char str1[128] = "Keep;learning;and;study;hard";
		printf("str1:\"%s\", splitChar:\"%s\"\n", str1, splitChar);
		
		char* ptr = strtok(str1, splitChar);
		for(; ptr != NULL; )
		{
			printf("%s\n", ptr);
			ptr = strtok(NULL, splitChar);
		}
		printf("strtok after, str1:%s\n", str1);
		
		printf("\n==========split1==========\n");
		char str2[128] = "Keep;learning;and;study;hard";
		printf("str2:\"%s\", splitChar:\"%s\"\n", str2, splitChar);
		int i;
		int ret = 1;
		char result[128];
		int strLen = strlen(str2);
		int resultLen = sizeof(result);
		for(i=1; ret>0; i++)
		{
			memset(result, 0, sizeof(result));
			ret = split(str2, strLen, splitChar, i, result, resultLen);
			if(ret>0)
			{
				printf("%s\n", result);
			}
		}
		printf("split after, str2:%s\n", str2);
	}
	
	{
		const char* splitChar = "##";
		printf("\n==========strtok2==========\n");
		char str1[128] = "Keep##learning##and##study##hard";
		printf("str1:\"%s\", splitChar:\"%s\"\n", str1, splitChar);
		
		char* ptr = strtok(str1, splitChar);
		for(; ptr != NULL; )
		{
			printf("%s\n", ptr);
			ptr = strtok(NULL, splitChar);
		}
		printf("strtok after, str1:%s\n", str1);
		
		printf("\n==========split2==========\n");
		char str2[128] = "Keep##learning##and##study##hard";
		printf("str2:\"%s\", splitChar:\"%s\"\n", str2, splitChar);
		int i;
		int ret = 1;
		char result[128];
		int strLen = strlen(str2);
		int resultLen = sizeof(result);
		for(i=1; ret>0; i++)
		{
			memset(result, 0, sizeof(result));
			ret = split(str2, strLen, splitChar, i, result, resultLen);
			if(ret>0)
			{
				printf("%s\n", result);
			}
		}
		printf("split after, str2:%s\n", str2);
	}
	return 0;
}

三、测试结果

四、总结
    strtok()函数介绍
 

详情请查询man手册，man strtok