1. Program and program structure
Program concept: a program written by a computer in order to realize a certain function
Sequence structure: execute in the order of the program
Select the structure: judge according to the given conditions, and determine the next step of execution by the result of the judgment
Cyclic structure: within the scope of the conditions, repeated execution
The essence of the condition is ultimately a Boolean value
2: if select structure
Concept: It is a grammatical structure that is processed according to conditions
Usage: When the first condition is not established, the second condition is executed, and the else is not satisfied.
Example:
if (condition 1)
{ program executed after condition 1 is satisfied } else if (condition 2) { program executed after condition 1 is not satisfied, condition 2 is satisfied } else { program executed when neither condition is satisfied }
3: switch structure
Concept: used to deal with fixed value branch
Usage:
int a = int.Parse(Console.ReadLine()); / 接收键盘输入 并转换为整数
switch(a)
{
case 1: / a=1执行的程序
Console.WriteLine("a=1"); /打印输出
break;
case 2: / a=2执行的程序
Console.WriteLine("a=2"); /打印输出
break;
default: / 都不满足 执行的程序
Console.WriteLine("a不等于1和2"); /打印输出
break;
}
Attributes:
Break: The meaning of breaking will make the code jump out of the entire loop body. C# must add this attribute after each.
Default: When it is not satisfied, execute the program
04: While and for loop structure
concept: within the scope of the establishment of conditions, repeated carried out;
while()：基本循环结构
while (条件)
{
条件成立之后循环执行的程序
}
do{
}while()：至少会执行一次，再判断条件
do
{
至少循环一次的程序
} while (条件)
for()：括号里填 初始值、循环条件、条件变化
for (条件变量：初始值; 循环条件; 条件变量的变化)
{
条件成立之后循环执行的程序
}
Attributes:
continue skip this round of loop, the next round will continue to
break out of the entire loop body, the code behind the loop body will be executed