strcpy
- Copies the C string pointed by source into the array pointed by destination, including the terminating null character (and stopping at that point).
- To avoid overflows, the size of the array pointed by destination shall be long enough to contain the same C string as source (including the terminating null character), and should not overlap in memory with source.
- 复制 source 所指向的空终止字节字符串，包含空终止符，到首元素为 destination 所指的字符数组。
- 若 destination 数组长度不足则行为未定义。
- 若字符串覆盖则行为未定义。
- 若 destination 不是指向字符数组的指针或 source 不是指向空终止字节字符串的指针则行为未定义。
char * strcpy ( char * destination, const char * source );
Parameters
destination
- Pointer to the destination array where the content is to be copied.
- 指向要写入的字符数组的指针
source
- C string to be copied.
- 指向要复制的空终止字节字符串的指针
Return Value
- destination is returned.
- 该函数返回一个指向最终的目标字符串 dest 的指针。
Example
//
// Created by zhangrongxiang on 2018/2/2 15:01
// File strcpy
//
#define __STDC_WANT_LIB_EXT1__ 0
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
int main(void) {
char *src = "Take the test.";
// src[0] = 'M' ; // 这会是未定义行为
char dst[strlen(src) + 1]; // +1 以适应空终止符
strcpy(dst, src);
dst[0] = 'M'; // OK
printf("src = %s\ndst = %s\n", src, dst);
#ifdef __STDC_LIB_EXT1__
set_constraint_handler_s(ignore_handler_s);
int r = strcpy_s(dst, sizeof dst, src);
printf("dst = \"%s\", r = %d\n", dst, r);
r = strcpy_s(dst, sizeof dst, "Take even more tests.");
printf("dst = \"%s\", r = %d\n", dst, r);
#endif
char string[10];
char str[] = "Hello World";
char *string2 = str;
printf("%s\n", string2); //Hello World\0
printf("%d\n", (int) sizeof(string)); //10
printf("%d\n", (int) strlen(string)); //0
printf("%d\n", (int) sizeof(string2)); //8
printf("%d\n", (int) strlen(string2)); //11
printf("%d\n", (int) sizeof(str)); //12
printf("%d\n", (int) strlen(str)); //11
/******************行为未定义********************************/
/** strcpy(string, string2);*/
/** printf("%s\n", string);*/
/** printf("%s\n", string2);*/
/***********************************************************/
char str2[sizeof(str)];
strcpy(str2, string2);
printf("%s\n", str2); //Hello World\0
strcpy(str2, "hi");
printf("%s\n", str2); //hi\0
//strcpy(str2, "everything is file"); //strcpy.c:53:5: warning: '__builtin_memcpy' writing 19 bytes into a region of size 12 overflows the destination [-Wstringop-overflow=]
//printf("%s\n", str2); //everything is file
char str3[] = "hello world!\0hello everyone";
printf("%s\n", str3); //hello world!
printf("%d\n", (int) strlen(str3)); //12
printf("%d\n", (int) sizeof(str3)); // 28
return EXIT_SUCCESS;
}
文章参考
