Highlights of this section:
- In-depth understanding of the use of strcpy function
- Learn the simulation implementation of the strcpy function
⚡strcpy
- Copies the C string pointed by source into the array pointed by destination, including the
terminating null character (and stopping at that point). - The source string must be terminated with '\0'.
- Will copy '\0' in the source string to the target space.
- The destination space must be large enough to accommodate the source string.
- The target space must be mutable.
The basic use of strcpy:
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include<string.h>
int main()
{
char arr1[] = "abcdef";
char arr2[20] = { 0 };
strcpy(arr2, arr1);//将arr1的数据拷贝到arr2中
printf("%s\n", arr2);
return 0;
}The result of the operation is as follows:
Here are a few related examples:
1. The source string must end with '\0', otherwise it cannot be copied correctly.
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include<string.h>
int main()
{
char arr1[] = { 'a','b','c' };
char arr2[20] = "xxxxxxxx";
strcpy(arr2, arr1);
printf("%s\n", arr2);
return 0;
}
//此程序会崩溃2. strcpy will copy '\0' in the source string to the target space.
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include<string.h>
int main()
{
char arr1[] = "abc\0def";
char arr2[20] = "xxxxxxxx";
strcpy(arr2, arr1);
printf("%s\n", arr2);
return 0;
}The result of running the code is as follows:
3. The destination space must be large enough to accommodate the source string.
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include<string.h>
int main()
{
char arr1[] = "abcdef";
char arr2[3] = { 0 };
strcpy(arr2, arr1);
printf("%s\n", arr2);
return 0;
}Program error:
4. The target space must be modifiable.
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include<string.h>
int main()
{
char* p = "abcdef"; //指针所指向的字符串为常量字符串，其内容不能被修改。
char arr2[20] = "JX_BC";
strcpy(p, arr2);
printf("%s\n", arr2);
return 0;
}
//该程序会崩溃⚡Simulate and implement the strcpy function
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include<assert.h>
//返回目标空间的起始位置
char* my_strcpy(char* dest, const char* src)//源头的数据不能发生变化，因此加上const进行保护
{
char* start = dest;
assert(dest && src);//断言保证两个指针有效
while (*dest++ = *src++)
{
;
}
return start;
}
int main()
{
char arr1[] = "abcdef";
char arr2[20] = { 0 };
my_strcpy(arr2, arr1);
printf("%s\n", arr2);
//printf("%s\n", my_strcpy(arr2, arr1));
return 0;
}The result of running the code is as follows:
Thank you for reading this blog. It took a long time to create it. Friends think my blog is helpful to you. You may wish to leave your likes and favorites, follow me, and show you a different C language.
