5. C language uses functions to realize string copying (does not use strcpy() function) (contains multiple methods)
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(1) The first method: use array subscript access (recommended)
#include<stdio.h>
//第一种方法:使用数组下标访问
void Copy1(char*des,char*src)//des是目标，src是源字符串
{
int i;
for(i=0;src[i]!='\0';i++)//当src[i]出现'\0'时，代表字符串遍历结束
{
des[i]=src[i];//给des[i]赋值
}
des[i]='\0';//给复制好的des[i]的结尾加上'\0'，代表字符串的结束
}
int main()
{
char arr[10]="abcdefg";
char brr[10];
Copy1(brr,arr);//调用函数1
printf("brr是%s",brr);//输出复制好的字符串数组brr
printf("\n");
return 0;
}
Execution result
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(2) The second method: using pointer dereference to access the array (not quite recommend)
#include<stdio.h>
//第一种方法:使用指针解引用访问(原理：利用p[i]等价于*(p+i))
void Copy2(char*des,char*src)//des是目标，src是源字符串
{
int i;
for (i = 0; *(src+i)!='\0'; i++)//当src出现'\0'时，代表字符串遍历结束
{
*(des+i)=*(src+i);//给des赋值
}
*(des+i)='\0';//给复制好的des的结尾加上'\0'，代表字符串的结束
}
int main()
{
char arr[10]="abcdefg";
char brr[10];
Copy2(brr,arr);//调用函数2
printf("brr是%s",brr);//输出复制好的字符串数组brr
printf("\n");
return 0;
}
Results of the
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(3) The third method: use pointer operations, move pointers to access array elements (very very important )
#include<stdio.h>
void Copy3(char* des, char* src)//利用指针操作，指针自行移动，*******非常非常非常重要********。
{
/*while (*src != '\0')
{
*des = *src;
src++;
des++;
}*/
for (; *src != '\0'; src++, des++)//与上面注释代码二选一即可
{
*des = *src;
}
*des = '\0';
}
int main()
{
char arr[10]="abcdefg";
char brr[10];
Copy3(brr,arr);//调用函数3
printf("brr是%s",brr);//输出复制好的字符串数组brr
printf("\n");
return 0;
}
Execution result
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(4) The fourth type: one line of code (not recommended)
#include<stdio.h>
void Copy4(char* des, char* src)
{
while (*des++ = *src++);//经典代码，不建议使用//
//技巧一：int i = 10; int j = i++;
//技巧二：int i=10;if(i)
}
int main()
{
char arr[10]="abcdefg";
char brr[10];
Copy4(brr,arr);//调用函数4
printf("brr是%s",brr);//输出复制好的字符串数组brr
printf("\n");
return 0;
}
Operation result
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Day4 2020-12-17 Thursday, sunny
Sometimes restless like fire, sometimes gentle like water, sometimes quiet as if living in an ivory tower, and sometimes mixed in the crowd with ease. Sometimes I cried and pierced my heart, and sometimes laughed tremblingly. Sometimes pretentious, sometimes arrogantly humble. What's wrong with this? The name of the disease is love.
