C language mathematical formula writing, a mathematical formula C expression, how to write this?

Reason for the error:

a=4/(8*n+1);

4 is integer data, n is integer data, 8*n+1 is still integer data, 4 (8*n+1) becomes integer data divided by integer data, the result is integer data, the decimal part is automatically rounded, and then the integer data is assigned to the double data, the result is not right, because a part of the value is rounded in the middle.

Here's another simple example:

double a;

a=4/5;After this statement is executed, the result of a is a=; After this statement is executed, the result of a is:

Amend the statement to read:

a=;That's it......

This is an implicit type conversion problem in C, and you can take a look back at the knowledge ...... in this part

<><There are 8 must-memorize classic programs in the C language

1. C language must memorize the first multiplication table of 8 classical programs

Output 9*9 multiplication formulas in C. There are 9 rows and 9 columns, I control the row, and J control the column.

2. C language must memorize 4x4 arrays of 8 classical programs

The function of the following program is to rotate a 4x4 array counterclockwise 90 degrees and output, requiring the data of the original array to be input randomly, and the new array is output in the form of 4 rows and 4 columns, please improve the program in the blank.

3. C language must memorize 8 classical questions related to the classical procedures of the god hall

There is a pair of rabbits, from the third month after birth to a pair of rabbits every month, the baby rabbit to the third month after the birth of a pair of rabbits every month, if the rabbits do not die, ask what is the total number of rabbits per month? The pattern of rabbits is the sequence 1, 1, 2, 3, 5, 8, 13, 21"

4. C language must memorize 8 elements of classical programs

The number determines how many prime numbers there are between 101 and 200, and outputs all prime numbers and the number of prime numbers.

Program Analysis: The method of judging prime numbers: remove 2 to sqrt (this number) with a number, and if it is divisible, it means that this number is not a prime number but a prime number.

5. C language must memorize 8 classic programs related to the completion of the stove**

If a number happens to be equal to the sum of its factors, it is called a "complete number". For example, 6 = 1 + 2 + 3Program to find all finishes up to 1000.

6. C language must memorize the triangle printing of 8 classic programs

Programmatically print a right-angled Yang Hui triangle.

7. C language must memorize the reverse output of 8 classic programs

Improve the program to implement the output of the input strings in reverse order, such as the input of Windows output SWODNIW.

8. The ninth C language must memorize 8 classic programs

The function of the following procedure is to remove the characters stored in c from the character array s.

Let's say the variable is already defined:

v*t+