从nsdata获取字节会附加额外的垃圾字符

Question

我试图将nsdata中的字节转换为char *，但char *的长度大于nsdata的长度，并包含最后附加的额外垃圾字符。代码：

 NSData * newData=[self dataFromHexString:trimmedHex];
 NSLog(@"new data length %d",[newData length]);
 char * ciphertext=(char*)[newData bytes];
 NSLog(@"length of ciphertext %zd",strlen(ciphertext));

日志：

2013-08-02 17:02:28.175 AES[4187:11303] new data length 128
2013-08-02 17:02:28.176 AES[4187:11303] length of ciphertext 144

从早上开始坚持这一点。:(

const char * ciphertextTemp=(const char*)[newData bytes];
char ciphertext[[newData length]+1];
for (int len=0; len<[self length];len++) {
    ciphertext[len]=ciphertextTemp[len];
}
ciphertext[[self length]]='\0';

Answer 1

可能是0 - char ciphertext指向的序列缺少终结符吗？

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<强>更新

而不是

for (int len=0; len<[self length];len++) {
  ciphertext[len]=ciphertextTemp[len];
}
ciphertext[[self length]]='\0';

你可以这样做：

strncpy(ciphertext, ciphertextTemp, [newData length]);
ciphertext[[self length] - 1]='\0';