C - C++ - strcpy function

ゝ一纸荒年。 2023-01-03 12:42 100阅读 0赞

# **C - C++ - strcpy function** #

定义在 头文件。

char *strcpy (char *destination, const char *source);

## 1. Copy string - 复制字符串 ##

Copies the C string pointed by `source` into the array pointed by `destination`, including the terminating null character (and stopping at that point).  
将 `source` 指向的 C 字符串复制到 `destination` 指向的数组中，包括终止的空字符 (并在该位置停止)。

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`.  
为避免溢出，`destination` 指向的数组的大小应足够长，以包含与 `source` 相同的 C 字符串 (包括终止空字符)，并且在内存中不应与 `source` 重叠。

## 2. Parameters ##

`destination`  
Pointer to the destination array where the content is to be copied.  
指向要在其中复制内容的目标数组的指针。

`source`  
C string to be copied.  
要复制的 C 字符串。

## 3. Return Value ##

`destination` is returned.  
返回 `destination`。

## 4. Example ##

str1: yong qiang
    str2: yong qiang
    str3: cheng
    请按任意键继续. . .

string copy，strcpy：字符串复制

strcpy 把含有 `'\0'` 结束符的字符串复制到另一个地址空间，返回值的类型为 `char *`。把从 src 地址开始且含有 NULL 结束符的字符串复制到以 dest 开始的地址空间。src 和 dest 所指内存区域不可以重叠且 dest 必须有足够的空间来容纳 src 的字符串。如果目标数组 dest 不够大，而源字符串的长度又太长，可能会造成缓冲溢出的情况。

## 5. yongqiang cheng - strcpy ##

void yong_strcpy(char *dest, const char *src)
    {
    	if (NULL == dest || NULL == src)
    	{
    		// TODO - yongqiang cheng
    		return;
    	}
    
    	int i = 0;
    	while (src[i] != '\0')
    	{
    		dest[i] = src[i];
    		i++;
    	}
    
    	dest[i] = src[i];
    }
    
    void qiang_strcpy(char dest[], const char src[])
    {
    	if (NULL == dest || NULL == src)
    	{
    		// TODO - yongqiang cheng
    		return;
    	}
    
    	int i = 0;
    	while ((dest[i] = src[i]) != '\0')
    	{
    		i++;
    	}
    }

### 5.1 yong\_strcpy ###

//============================================================================
    // Name        : std::strlen
    // Author      : Yongqiang Cheng
    // Version     : Version 1.0.0
    // Copyright   : Copyright (c) 2019 Yongqiang Cheng
    // Description : Hello World in C++, Ansi-style
    //============================================================================
    
    #ifndef _CRT_SECURE_NO_WARNINGS
    #define _CRT_SECURE_NO_WARNINGS
    #endif
    
    #include <stdio.h>
    #include <string.h>
    
    void yong_strcpy(char *dest, const char *src)
    {
    	if (NULL == dest || NULL == src)
    	{
    		// TODO - yongqiang cheng
    		return;
    	}
    
    	int i = 0;
    	while (src[i] != '\0')
    	{
    		dest[i] = src[i];
    		i++;
    	}
    
    	dest[i] = src[i];
    }
    
    int main()
    {
    	char str1[] = "yong qiang";
    	char str2[40];
    	char str3[40];
    	yong_strcpy(str2, str1);
    	yong_strcpy(str3, "cheng");
    	printf("str1: %s\nstr2: %s\nstr3: %s\n", str1, str2, str3);
    
    	return 0;
    }

str1: yong qiang
    str2: yong qiang
    str3: cheng
    请按任意键继续. . .

### 5.2 qiang\_strcpy ###

//============================================================================
    // Name        : std::strlen
    // Author      : Yongqiang Cheng
    // Version     : Version 1.0.0
    // Copyright   : Copyright (c) 2019 Yongqiang Cheng
    // Description : Hello World in C++, Ansi-style
    //============================================================================
    
    #ifndef _CRT_SECURE_NO_WARNINGS
    #define _CRT_SECURE_NO_WARNINGS
    #endif
    
    #include <stdio.h>
    #include <string.h>
    
    void yong_strcpy(char *dest, const char *src)
    {
    	if (NULL == dest || NULL == src)
    	{
    		// TODO - yongqiang cheng
    		return;
    	}
    
    	int i = 0;
    	while (src[i] != '\0')
    	{
    		dest[i] = src[i];
    		i++;
    	}
    
    	dest[i] = src[i];
    }
    
    void qiang_strcpy(char dest[], const char src[])
    {
    	if (NULL == dest || NULL == src)
    	{
    		// TODO - yongqiang cheng
    		return;
    	}
    
    	int i = 0;
    	while ((dest[i] = src[i]) != '\0')
    	{
    		i++;
    	}
    }
    
    int main()
    {
    	char str1[] = "yong qiang";
    	char str2[40];
    	char str3[40];
    	qiang_strcpy(str2, str1);
    	qiang_strcpy(str3, "cheng");
    	printf("str1: %s\nstr2: %s\nstr3: %s\n", str1, str2, str3);
    
    	return 0;
    }

str1: yong qiang
    str2: yong qiang
    str3: cheng
    请按任意键继续. . .

## 6. yongqiang cheng - strncpy ##

void yong_strncpy(char *dest, const char *src, const int len)
    {
    	if (NULL == dest || NULL == src)
    	{
    		// TODO - yongqiang cheng
    		return;
    	}
    
    	for (int i = 0; i < len; ++i)
    	{
    		dest[i] = src[i];
    	}
    
    	dest[len] = '\0';
    }

### 6.1 yong\_strncpy ###

//============================================================================
    // Name        : std::strlen
    // Author      : Yongqiang Cheng
    // Version     : Version 1.0.0
    // Copyright   : Copyright (c) 2019 Yongqiang Cheng
    // Description : Hello World in C++, Ansi-style
    //============================================================================
    
    #ifndef _CRT_SECURE_NO_WARNINGS
    #define _CRT_SECURE_NO_WARNINGS
    #endif
    
    #include <stdio.h>
    #include <string.h>
    
    void yong_strncpy(char *dest, const char *src, const int len)
    {
    	if (NULL == dest || NULL == src)
    	{
    		// TODO - yongqiang cheng
    		return;
    	}
    
    	for (int i = 0; i < len; ++i)
    	{
    		dest[i] = src[i];
    	}
    
    	dest[len] = '\0';
    }
    
    int main()
    {
    	char str1[] = "yong qiang";
    	char str2[40];
    	char str3[40];
    	yong_strncpy(str2, str1, 3);
    	yong_strncpy(str3, "cheng", 5);
    	printf("str1: %s\nstr2: %s\nstr3: %s\n", str1, str2, str3);
    
    	return 0;
    }

str1: yong qiang
    str2: yon
    str3: cheng
    请按任意键继续. . .

## References ##

[http://www.cplusplus.com/reference/cstring/strcpy/][http_www.cplusplus.com_reference_cstring_strcpy]

[http_www.cplusplus.com_reference_cstring_strcpy]: http://www.cplusplus.com/reference/cstring/strcpy/