Help me analyze these C programming statements in detail

It is a system file that provides functions such as input and output. The include statement is used to include this header file in the program. The effect of j*=-1 is to change the positive and negative of j.

sum +=i*j;The function of this sentence is to add the result of multiplying i and j to sum each time. In the end, sum will be equal to 1-3+5-7+......99。for the output content.

i-3+5-7+……99= is a string. It will be displayed on your computer. d is the format of the sum output.

i.e. output in decimal form. i should be 1. It's a mistake.

The second one is simple. It's bubbling sorting. Sort the 10 numbers from smallest to largest.

Faint to death, I don't understand so much, most of these books are available.

There is less explanation in the include book, so let me explain.

include is to add the contents of this file as it is, called a header file, why include it? Because we use the printf function in our program; The definition and declaration of this function are in the header file.

void is used to declare a valueless type.

For example, using void to declare a function indicates that the function has no return value.

void main()

define is used to define a macro.

For example, define abc 123

Once the macro is defined, the compiler replaces all abc in ** with 123 before compiling

<>Open Quality Check. txt" code piece;

Write data from the information structure to the file.

If you reach the end of the file, quit.

Information attributes include id and name, and the specific meanings must be referred to the relevant documentation or the definition notes of information.

Structs: In C, a struct is a data structure, which is a class of aggregated data types in C. Structs can be declared as variables, finger pins, arrays, etc., to implement more complex data structures.

A struct is also a collection of elements that become members of a struct, and these members can be of different types, and members are usually accessed by name.

Structs are the same as other types of underlying data types, such as int and char, except that structs can be made into the data type you want. for easy future use.

The role of structs in functions is not to change gradients, but to encapsulate them. The benefit of encapsulation is that it can be reused. So that the user doesn't have to care what it is, just use it according to the definition.

In real projects, structures exist in large numbers. Structs are often used by developers to encapsulate properties to compose new types, but because C internal programs are relatively simple, developers usually use structs to create new properties in order to simplify operations.