c学习笔记--4 循环控制语句 if for while do

好久之前的了，学习c语言的笔记。
依旧是老套路，从基础的变量类型，到函数定义一步步学起

#include <stdio.h>
#include <string.h>

//控制语句 这个在不同语言里几乎都不变
void test5()
{
	int a = 4;

	//if判断语句
	if (0 < a < 2)
		printf("var is level 1\n");
	else if (a >= 2 && a <= 5)
	{
		printf("var is level 2\n");
	}
	else
	{
		printf("var is level 3\n");
	}


	//switch 分支语句
	switch (a)
	{
	case 1:printf("var vlue is 1\n"); break;
	case 2:printf("var vlue is 2\n"); break;
	case 3:printf("var vlue is 3\n"); break;
	case 4:printf("var vlue is 4\n"); break;
	default:printf("var vlue is out of control\n"); break;
	}


	//for循环语句
	for (int i = 0; i <= a && i != 3; i++)
	{
		printf("for vlue is :%d\n", i);
	}

	
	//while 循环
	int j = 0;
	while (j <= a)
	{
		printf("while vlue is :%d\n", j);
		j++;
	}


	//do循环 跟while相比 至少循环一下 因为循环体先执行后判断
	j = 0;
	do 
	{
		printf("do - while vlue is :%d\n", j);
		j++;
	} 
	while (j <= 4);


	//goto语句的标签 后期可以跳转到这里执行
aaa:
	j--;
	printf("goto j vlue is :%d\n", j);
	if (j > 1)
		goto aaa;


	gets();

}