这段代码应该加载两个文件并比较它们的字节并输出差异,但由于某种原因,即使使用相同的文件,它也会输出差异,并且似乎忽略了我的格式化。
任何帮助都将是非常感激的。
谢谢。
int main(int argc, const char * argv[])
{
@autoreleasepool {
NSString *pathA = [[NSBundle mainBundle] pathForResource:@"original/testfile" ofType:@""];
NSFileHandle *fileA = [NSFileHandle fileHandleForReadingAtPath:pathA];
NSString *pathB = [[NSBundle mainBundle] pathForResource:@"updated/testfile" ofType:@""];
NSFileHandle *fileB = [NSFileHandle fileHandleForReadingAtPath:pathB];
unsigned long long sizeofFile = [fileA seekToEndOfFile];
[fileA seekToFileOffset:0];
[fileB seekToFileOffset:0];
unsigned int fileaValue;
unsigned int filebValue;
for (int i = 0; i <= sizeofFile; i++) {
[[fileA readDataOfLength:1] getBytes:&fileaValue];
[[fileB readDataOfLength:1] getBytes:&filebValue];
if (fileaValue != filebValue)
NSLog(@"File A %02x File B %02x at offset %u:",fileaValue,filebValue,i);
}
[fileA closeFile];
[fileB closeFile];
}
return 0;
}
示例输出
2013-03-13 13:50:50.580 compareFile[12055:303] File A 7fce File B 5fbff9ce at offset 0:
2013-03-13 13:50:50.581 compareFile[12055:303] File A 7ffa File B 5fbff9fa at offset 1:
我认为问题可能是你选择的数据类型(如果你想要一个单字节,然后使用uint8_t
),几乎可以肯定你在for
循环中使用<=
:
uint8_t fileaValue;
uint8_t filebValue;
for (unsigned i = 0; i < sizeofFile; i++) { // NOT <=
[[fileA readDataOfLength:1] getBytes:&fileaValue];
[[fileB readDataOfLength:1] getBytes:&filebValue];
if (fileaValue != filebValue)
NSLog(@"File A %02x File B %02x at offset %u:", (unsigned)fileaValue, (unsigned)filebValue,i);
}
(注意NSLog()
调用中的强制转换,以便正确打印值)。
还检查readDataOfLength
的成功是按顺序给定的文件I/O是一个常见的错误原因。