##ObjC Data Tyep Size 确定32位和64位下各数据类型占用的字节大小。

###32位下的情形 示例程序:

NSLog(@"32 bit 下 sizeof(char) = %lu 个字节", sizeof(char));
NSLog(@"32 bit 下 sizeof(unsigned char) = %lu 个字节", sizeof(unsigned char));
NSLog(@"32 bit 下 sizeof(short) = %lu 个字节", sizeof(short));
NSLog(@"32 bit 下 sizeof(unsigned short) = %lu 个字节", sizeof(unsigned short));
NSLog(@"32 bit 下 sizeof(int) = %lu 个字节", sizeof(int));
NSLog(@"32 bit 下 sizeof(unsigned int) = %lu 个字节", sizeof(unsigned int));
NSLog(@"32 bit 下 sizeof(long) = %lu 个字节", sizeof(long));
NSLog(@"32 bit 下 sizeof(unsigned long) = %lu 个字节", sizeof(unsigned long));
NSLog(@"32 bit 下 sizeof(long long) = %lu 个字节", sizeof(long long));
NSLog(@"32 bit 下 sizeof(unsigned long long) = %lu 个字节", sizeof(unsigned long long));
NSLog(@"32 bit 下 sizeof(BOOL) = %lu 个字节", sizeof(BOOL));
NSLog(@"32 bit 下 sizeof(bool) = %lu 个字节", sizeof(bool));
NSLog(@"32 bit 下 sizeof(float) = %lu 个字节", sizeof(float));
NSLog(@"32 bit 下 sizeof(double) = %lu 个字节", sizeof(double));
NSLog(@"32 bit 下 sizeof(int8_t) = %lu 个字节", sizeof(int8_t));
NSLog(@"32 bit 下 sizeof(int16_t) = %lu 个字节", sizeof(int16_t));
NSLog(@"32 bit 下 sizeof(int32_t) = %lu 个字节", sizeof(int32_t));
NSLog(@"32 bit 下 sizeof(int64_t) = %lu 个字节", sizeof(int64_t));
NSLog(@"32 bit 下 sizeof(uint8_t) = %lu 个字节", sizeof(uint8_t));
NSLog(@"32 bit 下 sizeof(uint16_t) = %lu 个字节", sizeof(uint16_t));
NSLog(@"32 bit 下 sizeof(uint32_t) = %lu 个字节", sizeof(uint32_t));
NSLog(@"32 bit 下 sizeof(uint64_t) = %lu 个字节", sizeof(uint64_t));
NSLog(@"32 bit 下 sizeof(unsigned char *) = %lu 个字节", sizeof(unsigned char *));
NSLog(@"32 bit 下 sizeof(uint8_t *) = %lu 个字节", sizeof(uint8_t *));
NSLog(@"32 bit 下 sizeof(size_t) = %lu 个字节", sizeof(size_t));

对应输出:

32 bit 下 sizeof(char) = 1 个字节
32 bit 下 sizeof(unsigned char) = 1 个字节
32 bit 下 sizeof(short) = 2 个字节
32 bit 下 sizeof(unsigned short) = 2 个字节
32 bit 下 sizeof(int) = 4 个字节
32 bit 下 sizeof(unsigned int) = 4 个字节
32 bit 下 sizeof(long) = 4 个字节
32 bit 下 sizeof(unsigned long) = 4 个字节
32 bit 下 sizeof(long long) = 8 个字节 
32 bit 下 sizeof(unsigned long long) = 8 个字节
32 bit 下 sizeof(BOOL) = 1 个字节
32 bit 下 sizeof(bool) = 1 个字节
32 bit 下 sizeof(float) = 4 个字节
32 bit 下 sizeof(double) = 8 个字节 
32 bit 下 sizeof(int8_t) = 1 个字节
32 bit 下 sizeof(int16_t) = 2 个字节
32 bit 下 sizeof(int32_t) = 4 个字节
32 bit 下 sizeof(int64_t) = 8 个字节
32 bit 下 sizeof(uint8_t) = 1 个字节
32 bit 下 sizeof(uint16_t) = 2 个字节
32 bit 下 sizeof(uint32_t) = 4 个字节
32 bit 下 sizeof(uint64_t) = 8 个字节
32 bit 下 sizeof(unsigned char *) = 4 个字节
32 bit 下 sizeof(uint8_t *) = 4 个字节
32 bit 下 sizeof(size_t) = 4 个字节

###64位下的情形

示例程序:

NSLog(@"64 bit 下 sizeof(char) = %lu 个字节", sizeof(char));
NSLog(@"64 bit 下 sizeof(unsigned char) = %lu 个字节", sizeof(unsigned char));
NSLog(@"64 bit 下 sizeof(short) = %lu 个字节", sizeof(short));
NSLog(@"64 bit 下 sizeof(unsigned short) = %lu 个字节", sizeof(unsigned short));
NSLog(@"64 bit 下 sizeof(int) = %lu 个字节", sizeof(int));
NSLog(@"64 bit 下 sizeof(unsigned int) = %lu 个字节", sizeof(unsigned int));
NSLog(@"64 bit 下 sizeof(long) = %lu 个字节", sizeof(long));
NSLog(@"64 bit 下 sizeof(unsigned long) = %lu 个字节", sizeof(unsigned long));
NSLog(@"64 bit 下 sizeof(long long) = %lu 个字节", sizeof(long long));
NSLog(@"64 bit 下 sizeof(unsigned long long) = %lu 个字节", sizeof(unsigned long long));
NSLog(@"64 bit 下 sizeof(BOOL) = %lu 个字节", sizeof(BOOL));
NSLog(@"64 bit 下 sizeof(bool) = %lu 个字节", sizeof(bool));
NSLog(@"64 bit 下 sizeof(float) = %lu 个字节", sizeof(float));
NSLog(@"64 bit 下 sizeof(double) = %lu 个字节", sizeof(double));
NSLog(@"64 bit 下 sizeof(int8_t) = %lu 个字节", sizeof(int8_t));
NSLog(@"64 bit 下 sizeof(int16_t) = %lu 个字节", sizeof(int16_t));
NSLog(@"64 bit 下 sizeof(int32_t) = %lu 个字节", sizeof(int32_t));
NSLog(@"64 bit 下 sizeof(int64_t) = %lu 个字节", sizeof(int64_t));
NSLog(@"64 bit 下 sizeof(uint8_t) = %lu 个字节", sizeof(uint8_t));
NSLog(@"64 bit 下 sizeof(uint16_t) = %lu 个字节", sizeof(uint16_t));
NSLog(@"64 bit 下 sizeof(uint32_t) = %lu 个字节", sizeof(uint32_t));
NSLog(@"64 bit 下 sizeof(uint64_t) = %lu 个字节", sizeof(uint64_t));
NSLog(@"64 bit 下 sizeof(unsigned char *) = %lu 个字节", sizeof(unsigned char *));
NSLog(@"64 bit 下 sizeof(uint8_t *) = %lu 个字节", sizeof(uint8_t *));
NSLog(@"64 bit 下 sizeof(size_t) = %lu 个字节", sizeof(size_t));

对应输出:

64 bit 下 sizeof(char) = 1 个字节
64 bit 下 sizeof(unsigned char) = 1 个字节
64 bit 下 sizeof(short) = 2 个字节
64 bit 下 sizeof(unsigned short) = 2 个字节
64 bit 下 sizeof(int) = 4 个字节
64 bit 下 sizeof(unsigned int) = 4 个字节
64 bit 下 sizeof(long) = 8 个字节
64 bit 下 sizeof(unsigned long) = 8 个字节
64 bit 下 sizeof(long long) = 8 个字节
64 bit 下 sizeof(unsigned long long) = 8 个字节
64 bit 下 sizeof(BOOL) = 1 个字节
64 bit 下 sizeof(bool) = 1 个字节
64 bit 下 sizeof(float) = 4 个字节
64 bit 下 sizeof(double) = 8 个字节
64 bit 下 sizeof(int8_t) = 1 个字节
64 bit 下 sizeof(int16_t) = 2 个字节
64 bit 下 sizeof(int32_t) = 4 个字节
64 bit 下 sizeof(int64_t) = 8 个字节
64 bit 下 sizeof(uint8_t) = 1 个字节
64 bit 下 sizeof(uint16_t) = 2 个字节
64 bit 下 sizeof(uint32_t) = 4 个字节
64 bit 下 sizeof(uint64_t) = 8 个字节
64 bit 下 sizeof(unsigned char *) = 8 个字节
64 bit 下 sizeof(uint8_t *) = 8 个字节
64 bit 下 sizeof(size_t) = 8 个字节

##总结 32 位与 64 位数据类型的主要区别是 long。在 32 位下 long 占 4 个字节，而在 64 位下 long 为 8 个字节。 建议：在进行较底层 iOS 程序开发的时候，建议使用与平台无关的显示的确定的数据类型。即 int8_t、int16_t、int32_t、int64_t、uint8_t、uint16_t、uint32_t、uint64_t。