strcat与strcpy的用法

Question

#include<stdio.h>
#include<string.h>
void main()
{
 char s1[30]={"people's republic of "};
 char s2[]={"china"};
 printf("%s\n",strcat(s1,s2));
 printf("%s\n%s\n",s1,s2);
 char s3[400]={"people's republic of ddww eegg "};
 char s4[8]={"china"};
 printf("%s\n",strcpy(s3,s4));
 printf("%s\n%s\n",s3,s4);
}

这个程序有两个警告，这的原因？

 warning C4996: 'strcat': This function or variable may be unsafe. Consider using strcat_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
1>        d:\program files\microsoft visual studio 9.0\vc\include\string.h(79) : 参见“strcat”的声明

 warning C4996: 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
1>        d:\program files\microsoft visual studio 9.0\vc\include\string.h(74) : 参见“strcpy”的声明

Answer 1

警告C4996的文档里面有说

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Answer 2

strcat不进行数组越界检测，所以windows认为它不安全。

让你用strcat_s这个代替

你要确认程序没问题，可以直接#pragma warning(disable:4996)

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