A small calculation problem in C, a small calculation problem in C, a calculation problem in C?

Oh, it's actually very simple, you first have to know their priority, this equation, you must have 1: first calculate the following a*a, you should know this, this does not count out is 144

Next 2: Execute a-=144; This step is equivalent to a=a-144; The result is a=-132;

3: From the above result, it has been calculated that a=-132;This is the key, and the last one is a+=-132; The result is equivalent to a=a+=-132; "Here a=-132 ha" The result is naturally -264.

I don't know if I'm talking too long-winded ......Hee-hee......I hope you understand, if you still don't know why you need to calculate that step first, it's best to look at the priority mentioned in the book.

Because a+=a-=a*a, it is calculated from right to left.

That is, a*a is calculated first, so the result is 144, because the value of a is still 12.

Secondly, it is calculated that a-=144

Because the value of a at this time has not changed, that is, a=a-144, therefore, the value of a is -132 Finally, a+=-132 is calculated, that is, a=a+132, so a=-264

Do you understand? If you don't understand, you can come to me directly :)

abs() is a function that Li Yu uses to calculate the absolute value of a floating-point number. The meaning of this loop statement is that when the absolute value of t is greater than or equal to 2e-6, ** in the loop body is executed. The specific explanation is as follows:

fabs() is a function that buries the absolute value of floating-point numbers, because there is no built-in absolute value function in C. The fabs() function is declared in the library and needs to be included before it can be used.

While is a loop statement in the C language, followed by an expression in parentheses to indicate a loop condition. Only if the expression in parentheses is true, the statement in the loop body will be executed. If the expression is false at the beginning, the statement inside the loop will not be executed.

In this loop, fabs(t) >2e-6 indicates that the statement in the loop will be executed when the absolute value of t is greater than or equal to 2e-6. If the absolute value of t is less than 2e-6, the statement in the loop body will not be executed, and the loop will end.

By changing the expression in the while statement, Nexian Rock can achieve different cycle conditions and operations in the loop body. In this example, when the absolute value of t is greater than or equal to 2e-6, the operation in the circulation body is repeated until the absolute value of t is less than 2e-6.

The printf() function is calculated from back to front.

Calculate -i --. first-8 is obtained, at which point i has become 7, and the same can be done.

The printf statement starts with the following arguments and then calculates the preceding arguments. That is, first -i--, then -i++, and note that i++ is to take i first, then ++, and i is first ++ and then i. As a result, it was.

The first thing to do is to convert 10 to binary.

The value is 1010

Then it's the inverse, then it's 0101

Converting it to decimal again is 5

a=10

AA's anti. Complement representation. Subtract one to negate.

Decimal - 11

Output-11

+i, which means that 1 is added first;

i++, which means i, and then self-adding;

i, i--the same way;

The first ++i adds 1 first, so the output is 9 (at this time i is already equal to 9);

the second --i, which subtracts 1 first, so the output is 8 (i=8 at this time);

The third i++, complete the operation first, and then add 1, so the output is 8 (at this time, i=9);

Four or five, since the priority of -(negative) [not subtraction operation] is higher than ++, and then refer to the above, think about it yourself, the answer is, -9 (i=10); -10(i=9）