09-对字符串复制，连接的研究

秒速五厘米 2022-12-21 03:09 143阅读 0赞

#include <stdio.h>
    #include <string.h>
    
    //字符串复制,将src的内容复制到des中, 方法1
    char *Mystrcpy1(char *des,char *src)
    {
        
    	int i = 0;
    	while(src[i] != '\0')//0
    	{
        
    		des[i] = src[i];
    		i++;
    	}
    	des[i] = '\0';
    
    	return des;//返回目标字符串的地址
    }
    
    //字符串复制,将src的内容复制到des中,方法2
    void Mystrcpy2(char *des,char *src)
    {
        
    	while(*src != '\0')
    	{
        
    		*des = *src;
    		des++;
    		src++;
    	}
    	*des = '\0';
    	printf("%s\n",des);
    }
    //字符串复制,将src的内容复制到des中,方法3
    void Mystrcpy3(char *des,char *src)
    {
        
    	while(*src != '\0')
    	{
        
    		*des++ = *src++;//等同*(des++) = *(src++);
    		//(*des)++ = (*src)++;//error
    	}
    	*des = '\0';
    	printf("%s\n",des);
    }
    
    //经典代码,必须记得
    void Mystrcpy(char *des,char *src)
    {
        
    	while(*des++ = *src++) ;
    }
    
    //将src连接到des的尾部,例如("abcde","xyz")->"abcdexyz"
    void Mystrcat1(char *des,char *src)
    {
        
    	//找到des的尾部
    	int i = 0;
    	while(des[i]!='\0') 
    		i++;
    
    	//复制
    	Mystrcpy(&des[i],src);
    }
    
    //将src连接到des的尾部,例如("abcde","xyz")->"abcdexyz"
    void Mystrcat(char *des,char *src)
    {
        
    	//找到des的尾部
    	while(*des != '\0')
    		des++;//不允许*des++单独出现
    
    	while(*des++ = *src++) ;
    }
    
    int main()
    {
        
    	char arr[10] = "abcde";
    	char brr[10] = "xyz";
    	char crr[10];
    	//brr = arr;//需求很多,数组不能整体赋值,error
    	//Mystrcpy(brr,arr);
    	//Mystrcpy(arr,brr);
    	//Mystrcat(arr,brr);
    	strcpy(crr,arr);
    	printf("%s\n",crr);
    	printf("%d\n",strlen("abc"));
    
    	//int xrr[] = {1,2,3};
    	//int yrr[3] = xrr;//error
    
    	return 0;
    }