#define nValue 5
#define mValue nValue + nValue
NSLog(@"print value m%d", mvalue);
mvalue = nValue + nValue = 10;
NSLog(@"print value m*m%d", mvalue*mvalue);
mvalue*mvalue = nValue + nValue * nValue + nValue = 5 + 5 * 5 + 5 = 35
NSLog(@"print value m *m * 5 == %d", mvalue * mvalue * 5);
mvalue * mvalue * 5 = nValue + nValue * nValue + nValue * 5 = 5 + 5 * 5 + 5 * 5 = 55;
因此我们定义宏时尽量要写括号
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