源字符串中得字符串进行查找替换

最新推荐文章于 2024-06-19 22:22:05 发布

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本文介绍了一个用于字符串查找和替换的C语言实现方法。通过自定义函数`Fun`，可以在源字符串中查找特定子串并用新子串进行替换。文章详细展示了如何计算字符串长度、定位目标子串以及执行替换操作的过程。

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/*
 * 【功能】 对源字符串中得字符串进行查找替换 并返回动态申请空间的指针 char* Fun(char* pSrc, char* pOldStr, char* pNewStr);
 *    【输入】pSrc   源字符串
 *      	pOldStr 需要被替换的字符串
 *     	    pNewStr 替换的新的字符串
 *    【返回】替换后的新的字符串的指针 
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX 10

//计算字符串长度
int lenString(char * str)
{
	int i = 0;
	while(str[i] != '\0')
	{
		i++;		
	}
	return i;
}
//查找符合条件的字符串
int findString(int startPosition, char *pSrc, char *pOldStr)
{
	int i = 0, position;
	
	while(pSrc[startPosition] != '\0' && pOldStr[i] != '\0')
	{
		if(pSrc[startPosition] == pOldStr[i])
		{
			startPosition++;
			i++;
		}
		else if(pSrc[startPosition] == pOldStr[0])
		{
			position = startPosition + 1;
			startPosition++;
			i = 1;
		}
		else
		{
			position = startPosition + 2;
			startPosition++;
			i = 0;
		}		
	}
	
	if(pOldStr[i] != '\0')
	{
		position = 0;
		return -1;
	}
	return position;
}
//替换字符
void repalceString(char * resultStr, char *pSrc, int len_OldStr, char *pNewStr, int position)
{
	int i = 0, j = 0, k = 0;
	while(pSrc[i] != '\0')
	{
		if(i == position -1)
		{
			while(pNewStr[j] != '\0')
			{
				resultStr[k] = pNewStr[j];
				j++;
				k++;
			}
			i += len_OldStr;
		}
		else
		{
			resultStr[k] = pSrc[i];
			i++;
			k++;
		}		
	}
	resultStr[k] = '\0';
}

char * Fun(char *pSrc, char *pOldStr, char *pNewStr)
{
	int len_Src, len_OldStr, len_NewStr;
	char *resultStr;
	int count[MAX]; //记录符合替换的字符位置
	int i = 0, startPosition = 0, position ,number;
	char *pSrc1;
	
	len_Src = lenString(pSrc);
	len_OldStr = lenString(pOldStr);
	len_NewStr = lenString(pNewStr);
	
	//查找字符串	
	while(1)
	{
		position = findString(startPosition, pSrc, pOldStr);
		if(position == -1)
			break;
		else
		{
			count[i] = position;
			startPosition = position + len_OldStr -1;
			i++;
		}	
	}	
	count[i] = -1;
	//替换字符串	
	pSrc1 = (char *)malloc(len_Src + i * (len_NewStr - len_OldStr));
	memcpy(pSrc1, pSrc, len_Src);

	resultStr = (char *)malloc(len_Src + i * (len_NewStr - len_OldStr));
	i = 0;
	
	while(count[i] != -1)
	{	
		repalceString(resultStr, pSrc1, len_OldStr, pNewStr, count[i]);
		memcpy(pSrc1, resultStr, sizeof(resultStr));
		i++;
	}
	
	return resultStr;
}


int main()
{
	char *pSrc = "aassdddffgghhaassdddffgg", *pOldStr = "dd", *pNewStr = "^_^";
	char *Result;
	
	Result = Fun(pSrc, pOldStr, pNewStr);
	
	printf("源字符串:%s\n需要替换的字符串:%s\n替换成字符串:%s\n", pSrc, pOldStr, pNewStr);
	
	if(Result == NULL)
		printf("没有找到需要替换的字符串\n");
	else
		printf("结果:%s\n", Result);
	
	return 0;
}