C language learning log 10.10

One .Switch-case

Format ：

switch( Control statement ){
case  Constant :
      sentence 
     ...
case  Constant ：
      sentence 
     ...
default：
      sentence 
     ...
}

Control expressions can only be integer results , Constants can be constants , It can also be an expression for constant calculation .

switch Statement can be regarded as a calculation based jump , After calculating the value of the control expression , The program will jump to the matching case（ Branch label ） It's about . The branch label just indicates swich Road signs at internal locations , After executing the last statement in the branch , If not at the back break, It will be executed in sequence to the following case Go inside , Until I met a break, perhaps switch End .

Two . Test for weight gain

#include<stdio.h>
int main(void)
{
	int H,x;
	double W;
	scanf("%d",&x);
	if(x>100&&x<=300){
		H=x;
	}
	W=(H-100)*0.9*2;
	printf("%.1f",W);
}

3、 ... and . Calculate the average and sum

#include<stdio.h>
int main(void)
{
	int a,b,c,d,Sum;
	double Average;
	scanf("%d %d %d %d",&a,&b,&c,&d);
	Sum=a+b+c+d;
	Average=(a+b+c+d)/4.0;
	printf("Sum = %d; Average = %.1f",Sum,Average);
	
}