[英]string concatenation with strncat leads to error in signedness
update: the point of whether char, signed char, or unsigned was ultimately moot here. 更新:在这里最终讨论的是char,signed char还是unsigned的问题。 it was more appropriate to use memcpy in this situation, since it works indiscriminately on bytes.
在这种情况下使用memcpy更合适,因为它可以不加区分地在字节上工作。
Couldn't be a simpler operation, but I seem to be missing a critical step. 不可能是一个简单的操作,但是我似乎缺少了关键的一步。 In the following code, I am attempting to fill
bufferdata
with buffer
for which the compiler warns me of a difference in signedness. 在下面的代码,我试图填补
bufferdata
与buffer
的,编译器警告我在符号性的差别。
unsigned char buffer[4096] = {0};
char *bufferdata;
bufferdata = (char*)malloc(4096 * sizeof(bufferdata));
if (! bufferdata)
return false;
while( ... )
{
// nextBlock( voidp _buffer, unsigned _length );
read=nextBlock( buffer, 4096);
if( read > 0 )
{
bufferdata = strncat(bufferdata, buffer, read); // (help)
// leads to: pointer targets in passing argument 2 of strncat differ in signedness.
if(read == 4096) {
// let's go for another chunk
bufferdata = (char*)realloc(bufferdata, ( strlen(bufferdata) + (4096 * sizeof(bufferdata)) ) );
if (! bufferdata) {
printf("failed to realloc\n");
return false;
}
}
}
else if( read<0 )
{
printf("error.\n");
break;
}
else {
printf("done.\n");
break;
}
}
显然,在您的编译器中char
是带signed char
,因此是警告消息。
char * strncat ( char * destination, char * source, size_t num );
so as your destination buffer is unsigned char so there will be a warning of sign. 因此,由于您的目标缓冲区是unsigned char,因此会出现符号警告。 You can either change your buffer to char array if signed is not necessary else you can ignore warnings using -w option in compiler.
您可以在不需要签名的情况下将缓冲区更改为char数组,否则可以在编译器中使用-w选项忽略警告。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.