# Study day 8

Time：2022-5-6

### C language

1. The general form of the for statement

1. For — loop structure

2. for（ ：）

3. ``````int a, sum = 0;
for (a = 1; a <= 100; a++)
{
sum = sum + a;
}
printf("sum=%d", sum);``````
4. A = 1 in parentheses is the initial value of the cyclic variable, a < = 100 is the condition for the end of the cyclic variable, a + + is the added value of the cyclic variable

5. The expression is 1, which can be omitted

6. ``````int a, sum = 0;
a = 1;// You can assign a value to it first - the same usage as the previous one
For (; a < = 100; a + +) // must have; If there is no sign, it will fail. It is only to omit expression 1, that is, a = 1
{
sum = sum + a;
}
printf("sum=%d", sum);``````
7. Expression 2 can also be omitted, but the end of break must be added, otherwise it will loop indefinitely

8. ``````int a, sum = 0;
a = 1;
For (;; a + +) // must have; If no, it will fail
{
sum = sum + a;
If (a > = 100) // conditions for ending the loop
break;  // The purpose is to end the cycle

}
printf("sum=%d", sum);``````
9. Effect omitted from expression 3

10. ``````int a, sum;

for (sum = 0,a = 1; a <= 100; )// Must have; If no, it will fail
{
sum = sum + a;

a++;// Omit expression 3 to ensure that the for loop can end normally

}
printf("sum=%d", sum);``````
11. sum = 0,a = 1;

``````1. Sum = 0, - comma expression
2. sum = 0,a = 1; —— Expression 1. There is a comma expression in expression 1``````
12. Expression 1, expression 2 and expression 3 in for can be omitted

2. For statement actual

3. Main description of the for statement

## Unified solution for converting code items by spring boot enumeration

Define structure and interface public class CodeItem { private String _itemText; private Object _itemValue; public CodeItem(){ } public CodeItem(String itemText, Object itemValue){ _itemText = itemText; _itemValue = itemValue; } public String get_itemText() { return _itemText; } public void set_itemText(String _itemText) { this._itemText = _itemText; } public Object get_itemValue() { return _itemValue; } public void set_itemValue(Object […]