0 basic C language (3)

Judge

Now we want to make a code to calculate the time difference .
Enter two times , Enter hours and minutes for each time , Then output the difference between the two times .
We give 1 spot 40 and 2 spot 10 branch , Two hours

int hour1,minute1;
int hour2,minute2;

scanf("%d %d",&hour1,minute1);
scanf("%d %d",&hour2,minute2);

We want to c Input two times, but do you want to subtract directly to get the difference between the two times . If we subtract separately , Then the minutely minus result we get will be less than 0.

int hour1,minute1;
int hour2,minute2;

scanf("%d %d",&hour1,minute1);
scanf("%d %d",&hour2,minute2);
int ih=hour2-hour1;
int im=minute2-minute1;
if(im<0){
    
	im=60+im;
	ih--;
}
printf(" The time difference is %d Hours %d branch .\n",ih,im);

We set up one if Conditional statement if if If the conditions are met, it will proceed if The output of the statement in .
This is a simple judgment .
We give the relation of calculating two values , This is called relational operation

Operator	significance
==	equal
！=	It's not equal
>	d Greater than
>=	Greater than or equal to
<	Less than
<=	Less than or equal to
Column 1	Column 2

All relational operators have a lower priority than arithmetic operations , But higher than the assignment operation .
To determine whether they are equal == and ！= The priority of is lower than others , Continuous relational operations are performed from left to right .
Next, we run the code of a change calculator
Want to make a change calculator , First, the user needs to do two operations 1. Enter the purchase amount ,2. Enter payment split face , The change computer performs corresponding actions according to these two values .
These are read into two inputs for calculation and judgment , Final output .

// initialization 
int price=0;
int bill=0;
// Read in the amount and face value 
printf(" Please enter the amount ：");
scanf("%d",&price);
printf(" Please enter the face value :");
scanf("%d",&bill);
// Calculate the change 
print(" I should call you :%d\n",bill-price);

In this code we add // Two slashes indicate a comment .
A comment that continues several lines , To write in the format of multi line comments , By a pair of characters "/“ Start , With ”/" end .
If the amount of the above code is greater than the face value , What should I do if the face value is not enough
We can use if Sentence to judge .

// initialization 
int price=0;
int bill=0;
// Read in the amount and face value 
printf(" Please enter the amount ：");
scanf("%d",&price);
printf(" Please enter the face value :");
scanf("%d",&bill);
// Calculate the change 
if(bill>=price){
    
	printf(" I should call you :%d\n",bill-price);
}
printf(" You don't have enough money \n");

When if When the statement of is not true, it will output “ You don't have enough money ”.