如何使用strncpy_s解决此问题 [英] How do I solve this issue with strncpy_s

问题描述

当我使用strncpy时出现错误：

错误C4996' strncpy '：此函数或变量可能不安全。请考虑使用strncpy_s代替。禁用弃用，请使用_CRT_SECURE_NO_WARNINGS。



当我尝试' strncpy_s '时出现错误：

错误（活动）E0304没有重载函数实例strncpy_s匹配参数列表



我尝试过：

When I use "strncpy" I had the error:
"Error C4996 'strncpy': This function or variable may be unsafe. Consider using strncpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS."

and when I try 'strncpy_s' I had the error:
"Error (active) E0304 no instance of overloaded function "strncpy_s" matches the argument list"

What I have tried:

#include <stdio.h>  
#include <stdlib.h>  
#include <string.h>  
#include <crtdbg.h>  // For _CrtSetReportMode  
#include <errno.h> 
bool GetWord(char* theString,
	char* word, int& wordOffset);

// driver program
int main()
{
	const int bufferSize = 255;
	char buffer[bufferSize + 1]; // hold the entire string
	char word[bufferSize + 1]; // hold the word
	int wordOffset = 0; // start at the beginning

	std::cout << "Enter a string : ";
	std::cin.getline(buffer, bufferSize);

	while (GetWord(buffer, word, wordOffset))
	{
		std::cout << "Got this word: " << word << std::endl;
	}
	return 0;
}

// function to parse words from a string.
bool GetWord(char* theString, char* word, int& wordOffset)
{
	if (theString[wordOffset] == 0) // end of string?
		return false;

	char *p1, *p2;
	p1 = p2 = theString + wordOffset; // point to the next word

									  // eat leading spaces
	for (int i = 0; i<(int)strlen(p1) && !isalnum(p1[0]); i++)
		p1++;

	// see if you have a word
	if (!isalnum(p1[0]))
		return false;

	// p1 now points to start of next word
	// point p2 there as well
	p2 = p1;

	// march p2 to end of word
	while (isalnum(p2[0]))
		p2++;

	// p2 is now at end of word
	// p1 is at beginning of word
	// length of word is the difference
	int len = int(p2 - p1);

	// copy the word into the buffer
	strncpy(word, p1, len);


	// null terminate it
	word[len] = '\0';

	// now find the beginning of the next word
	for (int j = int(p2 - theString); j<(int)strlen(theString)
		&& !isalnum(p2[0]); j++)
	{
		p2++;
	}

	wordOffset = int(p2 - theString);

	return true;
}

推荐答案

有两种可能的解决方案：

1.将_CRT_SECURE_NO_WARNINGS添加到项目中设置和使用strncpy（）;

2.使用

The are 2 possible solutions:
1. Add _CRT_SECURE_NO_WARNINGS to your project's settings and use strncpy();
2. Use

strncpy_s(word, p1, len);

strncpy [ ^ ]和 strncpy_s [ ^ ]有不同的签名，即 strncpy_s 需要目标字符串的大小作为附加参数。因此你必须这样称呼

strncpy[^] and strncpy_s[^] have different signatures, namely strncpy_s needs the size of the destination string as additional parameter. Hence you would have to call it this way

strncpy(word, word_size, p1, len);

（并且您必须相应地更改 GetWord 签名，以便传递 word_size ）。



另一种选择是忽略或取消警告。

(and you would have to change GetWord signature accordingly, in order to pass word_size).

Another option is ignoring or suppressing the warning.

您是否检查了文档 strncpy_s，_strncpy_s_l，wcsncpy_s，_wcsncpy_s_l，_mbsncpy_s，_ _ _ _ _ _ _ _ _ @ target =_ blanktitle =New Window> ^ ]？

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