sprintf使用问题

[大头猫]

sprintf (lpInBuffer1,"%x",(unsigned short)lpInBuffer[0]);
在lpInBuffer[0]存入ff转成16进制的数据
用上面的函数总得到ffff，怎么才能得到ff？

[jackyjkchen]

%02x

[lwtsea]

楼上正解

[至善者善之敌]

int main()
{
	int lpInBuffer[1]={255};
	char *lpInBuffer1=new char[10];
	sprintf(lpInBuffer1,"%x",(unsigned short)lpInBuffer[0]);
	cout<<lpInBuffer1<<endl;
	delete lpInBuffer1;
} 

[至善者善之敌]

修正一下上面的

int main()
{
	int lpInBuffer[1]={255};
	char *lpInBuffer1=new char[10];
	sprintf(lpInBuffer1,"%x",(unsigned short)lpInBuffer[0]);
	cout<<lpInBuffer1<<endl;
	delete [] lpInBuffer1;
} 

[mymtom]

原因是类型转换引起的
lpInBuffer[0] 的类型为char 0xff 也就是-1
(unsigned short)lpInBuffer[0]会将lpInBuffer[0]的符号位扩展称为0xffff

[Quote=引用 8 楼 mymtom 的回复:]

C/C++ code
sprintf (lpInBuffer1,"%x",(unsigned char)lpInBuffer[0]);
[/Quote]

[大头猫]

程序很严谨的。楼上的都不对",(unsigned short)lpInBuffer[0])写成byte)lpInBuffer[0])

[某某9]

%02x

[AnYidan]

[Quote=引用 1 楼 jackyjkchen 的回复:]

%02x
[/Quote]
++

[mymtom]

sprintf (lpInBuffer1,"%x",(unsigned char)lpInBuffer[0]);

[非鱼boy]

sprintf会默认按照32位输出，所以即使你的lpInBuffer1里存的是ff，输出的时候也会输出，ffff。个人观点，还没有验证。